Use mypy default follow import strategy
This was put in place as we were fixing up old annotations but isn't required at this point, so can safely remove and stick with mypy defaults (which is more strict)

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/27048?src=pr&el=h1) Report
> Merging [#27048](https://codecov.io/gh/pandas-dev/pandas/pull/27048?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/b4aa1d66ecc8d391e8003a0a398bd96fe956bfdf?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/27048/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/27048?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #27048      +/-   ##
==========================================
- Coverage      92%      92%   -0.01%     
==========================================
  Files         180      180              
  Lines       50754    50754              
==========================================
- Hits        46698    46695       -3     
- Misses       4056     4059       +3
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.64% <ø> (ø)` | :arrow_up: |
| #single | `41.82% <ø> (-0.1%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/27048?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/27048/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `88.88% <0%> (-11.12%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/27048/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `96.89% <0%> (-0.12%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/27048/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `90.94% <0%> (+0.1%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/27048?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/27048?src=pr&el=footer). Last update [b4aa1d6...db3d54d](https://codecov.io/gh/pandas-dev/pandas/pull/27048?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/27048?src=pr&el=h1) Report
> Merging [#27048](https://codecov.io/gh/pandas-dev/pandas/pull/27048?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/b4aa1d66ecc8d391e8003a0a398bd96fe956bfdf?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/27048/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/27048?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #27048      +/-   ##
==========================================
- Coverage      92%      92%   -0.01%     
==========================================
  Files         180      180              
  Lines       50754    50754              
==========================================
- Hits        46698    46695       -3     
- Misses       4056     4059       +3
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.64% <ø> (ø)` | :arrow_up: |
| #single | `41.82% <ø> (-0.1%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/27048?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/27048/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `88.88% <0%> (-11.12%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/27048/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `96.89% <0%> (-0.12%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/27048/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `90.94% <0%> (+0.1%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/27048?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/27048?src=pr&el=footer). Last update [b4aa1d6...db3d54d](https://codecov.io/gh/pandas-dev/pandas/pull/27048?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks @WillAyd 