CI: if no docstring, create error GL08 and don't validate - fix for numpydoc 1.9

[Dr-Irv]

validate_docstrings was failing with numpydoc 1.9 on cython methods that have no docstrings. When no docstring, there is nothing to validate.

Partially addresses the CI issue mentioned in #61740

[jbrockmendel]

is this an alternative to #61725?

[Dr-Irv]

is this an alternative to #61725?

Yes, and it allows us to use numpydoc 1.9

[mroeschke]

Thanks @Dr-Irv

[lumberbot-app]

Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

git checkout 2.3.x
git pull

2. Cherry pick the first parent branch of the this PR on top of the older branch:

git cherry-pick -x -m1 30a2e7fb239e63beab44c7c459517eb4d2908a0d

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

git commit -am "Backport PR #61744: CI: if no docstring, create error GL08 and don't validate - fix for numpydoc 1.9"

4. Push to a named branch:

git push YOURFORK 2.3.x:auto-backport-of-pr-61744-on-2.3.x

5. Create a PR against branch 2.3.x, I would have named this PR:

"Backport PR #61744 on branch 2.3.x (CI: if no docstring, create error GL08 and don't validate - fix for numpydoc 1.9)"

And apply the correct labels and milestones.

Congratulations — you did some good work! Hopefully your backport PR will be tested by the continuous integration and merged soon!

Remember to remove the Still Needs Manual Backport label once the PR gets merged.

If these instructions are inaccurate, feel free to suggest an improvement.

[jorisvandenbossche]

Backport -> #61745