DOC: FIx flake8 errors for whatsnew v0.7.* -v0.9.* rst
- [x] closes #24260
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/24273?src=pr&el=h1) Report
> Merging [#24273](https://codecov.io/gh/pandas-dev/pandas/pull/24273?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/c0371288ff125cad66bc8689ab425dd4cc11c64a?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/24273/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24273?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #24273   +/-   ##
=======================================
  Coverage   92.22%   92.22%           
=======================================
  Files         162      162           
  Lines       51785    51785           
=======================================
  Hits        47758    47758           
  Misses       4027     4027
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.62% <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/24273?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/24273?src=pr&el=footer). Last update [c037128...874280c](https://codecov.io/gh/pandas-dev/pandas/pull/24273?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/24273?src=pr&el=h1) Report
> Merging [#24273](https://codecov.io/gh/pandas-dev/pandas/pull/24273?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/4974758cf59e21b19fbf3b0943d896ebb223db0c?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/24273/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/24273?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #24273   +/-   ##
=======================================
  Coverage   92.22%   92.22%           
=======================================
  Files         162      162           
  Lines       51828    51828           
=======================================
  Hits        47799    47799           
  Misses       4029     4029
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.62% <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/24273?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/24273?src=pr&el=footer). Last update [4974758...b015b1e](https://codecov.io/gh/pandas-dev/pandas/pull/24273?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 can you merge master thanks!