[WIP] remove ci testing for python 2
- [x] closes #25216 
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25217?src=pr&el=h1) Report
> Merging [#25217](https://codecov.io/gh/pandas-dev/pandas/pull/25217?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/683c7b55f5195fdf4f524239066cbf6f1301f0e7?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25217/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25217?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #25217      +/-   ##
==========================================
+ Coverage   92.34%   92.35%   +<.01%     
==========================================
  Files         166      166              
  Lines       52314    52314              
==========================================
+ Hits        48311    48312       +1     
+ Misses       4003     4002       -1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.78% <ø> (ø)` | :arrow_up: |
| #single | `42.84% <ø> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25217?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/25217/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `88.05% <0%> (+0.09%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25217?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/25217?src=pr&el=footer). Last update [683c7b5...eb719e4](https://codecov.io/gh/pandas-dev/pandas/pull/25217?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/25217?src=pr&el=h1) Report
> Merging [#25217](https://codecov.io/gh/pandas-dev/pandas/pull/25217?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/683c7b55f5195fdf4f524239066cbf6f1301f0e7?src=pr&el=desc) will **increase** coverage by `<.01%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25217/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25217?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #25217      +/-   ##
==========================================
+ Coverage   92.34%   92.35%   +<.01%     
==========================================
  Files         166      166              
  Lines       52314    52314              
==========================================
+ Hits        48311    48312       +1     
+ Misses       4003     4002       -1
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.78% <ø> (ø)` | :arrow_up: |
| #single | `42.84% <ø> (-0.01%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/25217?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/25217/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `88.05% <0%> (+0.09%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25217?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/25217?src=pr&el=footer). Last update [683c7b5...eb719e4](https://codecov.io/gh/pandas-dev/pandas/pull/25217?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 FYI there is already #24942 and we are not quite ready to do this. Missed that one, sorry 