Fix ModuleNotFoundError: No module named 'pandas.formats'
Fixes `test_shim` failure:
```
================================== FAILURES ===================================
__________________________________ test_shim __________________________________

    def test_shim():
        # https://github.com/pandas-dev/pandas/pull/16059
        # Remove in 0.21
        with tm.assert_produces_warning(FutureWarning,
                                        check_stacklevel=False):
>           from pandas.formats.style import Styler as _styler  # noqa
E           ModuleNotFoundError: No module named 'pandas.formats'

X:\Python36\lib\site-packages\pandas\tests\io\formats\test_style.py:866: ModuleNotFoundError
```
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16239?src=pr&el=h1) Report
> Merging [#16239](https://codecov.io/gh/pandas-dev/pandas/pull/16239?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/2002da33b0a755fcf7ef64b2c87ca4252f0e7df0?src=pr&el=desc) will **decrease** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/16239/graphs/tree.svg?token=eZ4WkYLtcO&src=pr&width=650&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/16239?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #16239      +/-   ##
==========================================
- Coverage   90.24%   90.23%   -0.01%     
==========================================
  Files         164      164              
  Lines       50894    50894              
==========================================
- Hits        45930    45926       -4     
- Misses       4964     4968       +4
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.02% <ø> (ø)` | :arrow_up: |
| #single | `40.3% <ø> (-0.1%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/16239?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/16239?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/16239?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.58% <0%> (-0.1%)` | :arrow_down: |
| [pandas/\_version.py](https://codecov.io/gh/pandas-dev/pandas/pull/16239?src=pr&el=tree#diff-cGFuZGFzL192ZXJzaW9uLnB5) | `44.65% <0%> (+1.9%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/16239?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/16239?src=pr&el=footer). Last update [2002da3...588d838](https://codecov.io/gh/pandas-dev/pandas/pull/16239?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Thanks for catching this!