isort plotting, a handful of test dirs
- [ ] closes #xxxx
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Hello @jbrockmendel! Thanks for submitting the PR.

 - There are no PEP8 issues in the file [`pandas/plotting/_compat.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/plotting/_compat.py) !

 - There are no PEP8 issues in the file [`pandas/plotting/_converter.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/plotting/_converter.py) !

 - There are no PEP8 issues in the file [`pandas/plotting/_core.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/plotting/_core.py) !

 - There are no PEP8 issues in the file [`pandas/plotting/_misc.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/plotting/_misc.py) !

 - There are no PEP8 issues in the file [`pandas/plotting/_style.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/plotting/_style.py) !

 - There are no PEP8 issues in the file [`pandas/plotting/_timeseries.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/plotting/_timeseries.py) !

 - There are no PEP8 issues in the file [`pandas/plotting/_tools.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/plotting/_tools.py) !

 - There are no PEP8 issues in the file [`pandas/tests/generic/test_frame.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/generic/test_frame.py) !

 - There are no PEP8 issues in the file [`pandas/tests/generic/test_generic.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/generic/test_generic.py) !

 - There are no PEP8 issues in the file [`pandas/tests/generic/test_label_or_level_utils.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/generic/test_label_or_level_utils.py) !

 - There are no PEP8 issues in the file [`pandas/tests/generic/test_panel.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/generic/test_panel.py) !

 - There are no PEP8 issues in the file [`pandas/tests/generic/test_series.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/generic/test_series.py) !

 - There are no PEP8 issues in the file [`pandas/tests/tseries/offsets/conftest.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/tseries/offsets/conftest.py) !

 - There are no PEP8 issues in the file [`pandas/tests/tseries/offsets/test_fiscal.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/tseries/offsets/test_fiscal.py) !

 - There are no PEP8 issues in the file [`pandas/tests/tseries/offsets/test_offsets.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/tseries/offsets/test_offsets.py) !

 - There are no PEP8 issues in the file [`pandas/tests/tseries/offsets/test_offsets_properties.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/tseries/offsets/test_offsets_properties.py) !

 - There are no PEP8 issues in the file [`pandas/tests/tseries/offsets/test_ticks.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/tseries/offsets/test_ticks.py) !

 - There are no PEP8 issues in the file [`pandas/tests/tseries/offsets/test_yqm_offsets.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/tseries/offsets/test_yqm_offsets.py) !

 - There are no PEP8 issues in the file [`pandas/tests/tseries/test_frequencies.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/tseries/test_frequencies.py) !

 - There are no PEP8 issues in the file [`pandas/tests/tseries/test_holiday.py`](https://github.com/jbrockmendel/pandas/blob/00969a5267a77b77725e24065515f1d178b36468/pandas/tests/tseries/test_holiday.py) !

 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23957?src=pr&el=h1) Report
> Merging [#23957](https://codecov.io/gh/pandas-dev/pandas/pull/23957?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/0e7cf4814ae8f85dc90ed6d8e24f0459be0b75e3?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23957/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23957?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #23957   +/-   ##
=======================================
  Coverage   92.31%   92.31%           
=======================================
  Files         161      161           
  Lines       51471    51471           
=======================================
  Hits        47515    47515           
  Misses       3956     3956
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.7% <100%> (ø)` | :arrow_up: |
| #single | `42.43% <86.11%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/23957?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/plotting/\_style.py](https://codecov.io/gh/pandas-dev/pandas/pull/23957/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19zdHlsZS5weQ==) | `77.41% <100%> (ø)` | :arrow_up: |
| [pandas/plotting/\_converter.py](https://codecov.io/gh/pandas-dev/pandas/pull/23957/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb252ZXJ0ZXIucHk=) | `63.67% <100%> (ø)` | :arrow_up: |
| [pandas/plotting/\_tools.py](https://codecov.io/gh/pandas-dev/pandas/pull/23957/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL190b29scy5weQ==) | `78.77% <100%> (ø)` | :arrow_up: |
| [pandas/plotting/\_compat.py](https://codecov.io/gh/pandas-dev/pandas/pull/23957/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb21wYXQucHk=) | `87.5% <100%> (ø)` | :arrow_up: |
| [pandas/plotting/\_core.py](https://codecov.io/gh/pandas-dev/pandas/pull/23957/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19jb3JlLnB5) | `83.63% <100%> (ø)` | :arrow_up: |
| [pandas/plotting/\_misc.py](https://codecov.io/gh/pandas-dev/pandas/pull/23957/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL19taXNjLnB5) | `38.68% <100%> (ø)` | :arrow_up: |
| [pandas/plotting/\_timeseries.py](https://codecov.io/gh/pandas-dev/pandas/pull/23957/diff?src=pr&el=tree#diff-cGFuZGFzL3Bsb3R0aW5nL190aW1lc2VyaWVzLnB5) | `65.28% <100%> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23957?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23957?src=pr&el=footer). Last update [0e7cf48...82bc0f8](https://codecov.io/gh/pandas-dev/pandas/pull/23957?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks