Run Isort on tests/arrays single PR
- [x] partial #23334
- [x] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
Run `isort -rc pandas/tests/arrays/`
Hello @thoo! Thanks for submitting the PR.

 - There are no PEP8 issues in the file [`pandas/tests/arrays/categorical/test_algos.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/categorical/test_algos.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/categorical/test_analytics.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/categorical/test_analytics.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/categorical/test_api.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/categorical/test_api.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/categorical/test_constructors.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/categorical/test_constructors.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/categorical/test_dtypes.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/categorical/test_dtypes.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/categorical/test_indexing.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/categorical/test_indexing.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/categorical/test_operators.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/categorical/test_operators.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/categorical/test_repr.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/categorical/test_repr.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/sparse/test_arithmetics.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/sparse/test_arithmetics.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/sparse/test_array.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/sparse/test_array.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/sparse/test_dtype.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/sparse/test_dtype.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/sparse/test_libsparse.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/sparse/test_libsparse.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/test_datetimelike.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/test_datetimelike.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/test_integer.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/test_integer.py) !

 - There are no PEP8 issues in the file [`pandas/tests/arrays/test_interval.py`](https://github.com/thoo/pandas/blob/7564890a67b98facac9b0b9e2b1fd895bafcb3cd/pandas/tests/arrays/test_interval.py) !

 needs a rebase # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23346?src=pr&el=h1) Report
> :exclamation: No coverage uploaded for pull request base (`master@c238620`). [Click here to learn what that means](https://docs.codecov.io/docs/error-reference#section-missing-base-commit).
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/23346/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23346?src=pr&el=tree)

```diff
@@            Coverage Diff            @@
##             master   #23346   +/-   ##
=========================================
  Coverage          ?   92.22%           
=========================================
  Files             ?      169           
  Lines             ?    51258           
  Branches          ?        0           
=========================================
  Hits              ?    47274           
  Misses            ?     3984           
  Partials          ?        0
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.66% <ø> (?)` | |
| #single | `42.23% <ø> (?)` | |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23346?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/23346?src=pr&el=footer). Last update [c238620...e1867ce](https://codecov.io/gh/pandas-dev/pandas/pull/23346?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @jreback This one is also green. Thanks. thanks!