Fix flake8 issues on v22, v23 and v24rst
- [x] closes #24200, #24201 and #24202 
- [x] `flake8-rst source/whatsnew/v0.22.0.rst` and `flake8-rst source/whatsnew/v0.23.0.rst` 
This is related to #24177


# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24217?src=pr&el=h1) Report
> Merging [#24217](https://codecov.io/gh/pandas-dev/pandas/pull/24217?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/91802fb0accde031c3b6aca040a8b533a193fef6?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24217/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24217?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #24217   +/-   ##
=======================================
  Coverage   92.21%   92.21%           
=======================================
  Files         162      162           
  Lines       51763    51763           
=======================================
  Hits        47733    47733           
  Misses       4030     4030
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.61% <ø> (ø)` | :arrow_up: |
| #single | `43% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24217?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/24217?src=pr&el=footer). Last update [91802fb...70802af](https://codecov.io/gh/pandas-dev/pandas/pull/24217?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/24217?src=pr&el=h1) Report
> Merging [#24217](https://codecov.io/gh/pandas-dev/pandas/pull/24217?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/91802fb0accde031c3b6aca040a8b533a193fef6?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/24217/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24217?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #24217   +/-   ##
=======================================
  Coverage   92.21%   92.21%           
=======================================
  Files         162      162           
  Lines       51763    51763           
=======================================
  Hits        47733    47733           
  Misses       4030     4030
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.61% <ø> (ø)` | :arrow_up: |
| #single | `43% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24217?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/24217?src=pr&el=footer). Last update [91802fb...ac5aa75](https://codecov.io/gh/pandas-dev/pandas/pull/24217?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @datapythonista Thanks. I will definitely do it next time. 