DOC: Validate space before colon docstring parameters #23483
- [X] closes #23483
- [X] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [ ] whatsnew entry

Hello @dannyhyunkim! Thanks for submitting the PR.

 - There are no PEP8 issues in the file [`scripts/tests/test_validate_docstrings.py`](https://github.com/dannyhyunkim/pandas/blob/fa283d5c108a0dbd3612f7a02f0a3afd6afaa1ec/scripts/tests/test_validate_docstrings.py) !

 - There are no PEP8 issues in the file [`scripts/validate_docstrings.py`](https://github.com/dannyhyunkim/pandas/blob/fa283d5c108a0dbd3612f7a02f0a3afd6afaa1ec/scripts/validate_docstrings.py) !

 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23506?src=pr&el=h1) Report
> Merging [#23506](https://codecov.io/gh/pandas-dev/pandas/pull/23506?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/a197837c4067469478b13e491a21b58cb78ed165?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/23506/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/23506?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #23506   +/-   ##
=======================================
  Coverage   92.24%   92.24%           
=======================================
  Files         161      161           
  Lines       51318    51318           
=======================================
  Hits        47339    47339           
  Misses       3979     3979
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.63% <ø> (ø)` | :arrow_up: |
| #single | `42.31% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/23506?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/23506?src=pr&el=footer). Last update [a197837...4253b97](https://codecov.io/gh/pandas-dev/pandas/pull/23506?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @dannyhyunkim sorry this wasn't merged earlier. Can you please resolve the conflicts? @datapythonista I've had a go at resolving conflicts. Could you take a look? Also, how do I rerun the builds/tests? @dannyhyunkim, sorry about that, but seems like the CI failed with errors unrelated to your PR. Do you mind merging master into it again, so we trigger a new CI build? @datapythonista, done! Sorry I missed this before. Great work @dannyhyunkim !