Update python_requires to 3.5+
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26330?src=pr&el=h1) Report
> Merging [#26330](https://codecov.io/gh/pandas-dev/pandas/pull/26330?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/ee6b1318ff07806ead79dac8119ad9ce580afe1c?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/26330/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26330?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26330      +/-   ##
==========================================
- Coverage   92.04%   92.03%   -0.01%     
==========================================
  Files         175      175              
  Lines       52297    52297              
==========================================
- Hits        48137    48134       -3     
- Misses       4160     4163       +3
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.59% <ø> (ø)` | :arrow_up: |
| #single | `40.71% <ø> (-0.16%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26330?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26330/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `78.94% <0%> (-10.53%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/26330/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.01% <0%> (-0.12%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/26330/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `90.7% <0%> (+0.1%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26330?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/26330?src=pr&el=footer). Last update [ee6b131...32bdd58](https://codecov.io/gh/pandas-dev/pandas/pull/26330?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/26330?src=pr&el=h1) Report
> Merging [#26330](https://codecov.io/gh/pandas-dev/pandas/pull/26330?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/ee6b1318ff07806ead79dac8119ad9ce580afe1c?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/26330/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/26330?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #26330      +/-   ##
==========================================
- Coverage   92.04%   92.03%   -0.01%     
==========================================
  Files         175      175              
  Lines       52297    52297              
==========================================
- Hits        48137    48134       -3     
- Misses       4160     4163       +3
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.59% <ø> (ø)` | :arrow_up: |
| #single | `40.71% <ø> (-0.16%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/26330?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/26330/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `78.94% <0%> (-10.53%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/26330/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.01% <0%> (-0.12%)` | :arrow_down: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/26330/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `90.7% <0%> (+0.1%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/26330?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/26330?src=pr&el=footer). Last update [ee6b131...32bdd58](https://codecov.io/gh/pandas-dev/pandas/pull/26330?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Should we updated the classifiers in here as well? > Should we updated the classifiers in here as well?

Yes.  Let's do in a follow-up. Thanks @TomAugspurger !