Run isort at pandas/tests/io
- [ ] xref #23334
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`


merge master # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24532?src=pr&el=h1) Report
> Merging [#24532](https://codecov.io/gh/pandas-dev/pandas/pull/24532?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/b9284a2cd87fc305106fd75836dc96d7e00a0210?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24532/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24532?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #24532   +/-   ##
=======================================
  Coverage   31.88%   31.88%           
=======================================
  Files         166      166           
  Lines       52427    52427           
=======================================
  Hits        16714    16714           
  Misses      35713    35713
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `30.28% <ø> (ø)` | :arrow_up: |
| #single | `31.88% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24532?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/24532?src=pr&el=footer). Last update [b9284a2...41ee93e](https://codecov.io/gh/pandas-dev/pandas/pull/24532?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24532?src=pr&el=h1) Report
> Merging [#24532](https://codecov.io/gh/pandas-dev/pandas/pull/24532?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/71efe61b457892dbd7dce5ebba5d1cd364a8ebbd?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/24532/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24532?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #24532   +/-   ##
=======================================
  Coverage   92.32%   92.32%           
=======================================
  Files         166      166           
  Lines       52440    52440           
=======================================
  Hits        48416    48416           
  Misses       4024     4024
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.75% <100%> (ø)` | :arrow_up: |
| #single | `43.01% <66.66%> (ø)` | :arrow_up: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/24532?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/formats/style.py](https://codecov.io/gh/pandas-dev/pandas/pull/24532/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvc3R5bGUucHk=) | `96.69% <100%> (ø)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24532?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/24532?src=pr&el=footer). Last update [71efe61...8df2ab4](https://codecov.io/gh/pandas-dev/pandas/pull/24532?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 need a merge master can you merge again and something failng @thoo can you see if can get passing lgtm. ping on green. thanks @thoo 