CLN: Remove have_pytz (gh-17251)
- [x] closes #17251
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

lgtm assuming it passes. The Travis error was a ResourceWarning, seems unrelated. # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17266?src=pr&el=h1) Report
> Merging [#17266](https://codecov.io/gh/pandas-dev/pandas/pull/17266?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/6fe68325de93a5f745ff49eac57589d33a1d53c1?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/17266/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/17266?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17266      +/-   ##
==========================================
- Coverage   91.02%   91.01%   -0.02%     
==========================================
  Files         162      162              
  Lines       49539    49539              
==========================================
- Hits        45095    45087       -8     
- Misses       4444     4452       +8
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.79% <ø> (ø)` | :arrow_up: |
| #single | `40.25% <ø> (-0.07%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17266?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17266?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17266?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.72% <0%> (-0.1%)` | :arrow_down: |
| [pandas/core/indexes/datetimes.py](https://codecov.io/gh/pandas-dev/pandas/pull/17266?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW5kZXhlcy9kYXRldGltZXMucHk=) | `95.33% <0%> (+0.09%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17266?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/17266?src=pr&el=footer). Last update [6fe6832...a0cae1d](https://codecov.io/gh/pandas-dev/pandas/pull/17266?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Alright, in it goes.  Thanks @jbrockmendel !