Re-add py3.9 support to sage_autodoc.py

[kiwifb]

This PR corrects the fact the sage_autodoc.py changes needed for sphinx 8 dropped python 3.9 support. This is a consequence of the fact that sphinx 8 has dropped python 3.9.
Since we still want to support python 3.9, some support has to be re-introduced.
See #38549 (comment) and after.

📝 Checklist

• The title is concise and informative.
• The description explains in detail what this PR is about.
• I have linked a relevant issue or discussion.
• I have created tests covering the changes.
• I have updated the documentation and checked the documentation preview.

[mkoeppe]

In the CI, I see:

  [sagemath_doc_html-none] [spkg-install] [algebras ]   File "/sage/src/sage_docbuild/ext/sage_autodoc.py", line 1909, in get_doc
  [sagemath_doc_html-none] [spkg-install] [algebras ]     if sys.version_info[:2] < (3, 10):
  [sagemath_doc_html-none] [spkg-install] [algebras ] NameError: name 'sys' is not defined

[kiwifb]

I should have double checked that an import of sys was present.

[github-actions]

Documentation preview for this PR (built with commit 57f5d16; changes) is ready! 🎉
This preview will update shortly after each push to this PR.

[kiwifb]

Looks a lot healthier now.

[mkoeppe]

This error still shows up with Python 3.9:

[spkg-install] [spkg     ] Exception occurred:
[spkg-install] [spkg     ]   File "/Users/mkoeppe/s/sage/sage-rebasing/worktree-pristine/src/sage_docbuild/ext/sage_autodoc.py", line 1654, in import_object
[spkg-install] [spkg     ]     if isinstance(self.object, NewType | TypeVar):
[spkg-install] [spkg     ] TypeError: unsupported operand type(s) for |: 'function' and 'type'
[spkg-install] [spkg     ] The full traceback has been saved in /var/folders/38/wnh4gf1552g_crsjnv2vmmww0000gp/T/sphinx-err-0l5np5ke.log, if you want to report th

[kiwifb]

Hopefully, I will not have to make those into blocks conditional to the version of python. And they will be enough.

[mkoeppe]

[sagemath_doc_html-none] [spkg-install] [combinat ] Exception occurred:
[sagemath_doc_html-none] [spkg-install] [combinat ]   File "/Users/mkoeppe/s/sage/sage-rebasing/worktree-pristine/src/sage_docbuild/ext/sage_autodoc.py", line 674, in add_content
[sagemath_doc_html-none] [spkg-install] [combinat ]     for line, src in zip(more_content.data, more_content.items, strict=True):
[sagemath_doc_html-none] [spkg-install] [combinat ] TypeError: zip() takes no keyword arguments

[mkoeppe]

This does the trick, thanks very much!

[kiwifb]

And it breaks sphinx-8. I will need to add some try expect blocks. Since it is being merged, that will be another follow up.

[kiwifb]

@vbraun I see you have this in your merge tree, but it turns out it needs more work. Is it OK with you if I push some more commits or you'd prefer a follow up?

[vbraun]

you can keep working on it

[kiwifb]

@mkoeppe if you would like to check that it is still working for you on py3.9. Unless you find something not working, it should be the last tweak.

[kwankyu]

It works well with py3.9. LGTM.

[kiwifb]

Thanks!