gh-101100: Fix sphinx warnings in whatsnew/3.9

[sobolevn]

It used to be:

/Users/sobolev/Desktop/cpython/Doc/whatsnew/3.9.rst:426: WARNING: py:const reference target not found: fcntl.F_OFD_GETLK [ref.const] /Users/sobolev/Desktop/cpython/Doc/whatsnew/3.9.rst:426: WARNING: py:const reference target not found: fcntl.F_OFD_SETLK [ref.const] /Users/sobolev/Desktop/cpython/Doc/whatsnew/3.9.rst:426: WARNING: py:const reference target not found: fcntl.F_OFD_SETLKW [ref.const] /Users/sobolev/Desktop/cpython/Doc/whatsnew/3.9.rst:647: WARNING: py:attr reference target not found: random.Random.randbytes [ref.attr] /Users/sobolev/Desktop/cpython/Doc/whatsnew/3.9.rst:779: WARNING: py:func reference target not found: set.difference_update [ref.func] /Users/sobolev/Desktop/cpython/Doc/whatsnew/3.9.rst:1141: WARNING: py:func reference target not found: encodings.normalize_encoding [ref.func] 

I opened #136162 about the encodings part.

I had to use

:meth:`!set.difference_update` 

because stdtypes defines this method as frozenset.difference_update

• Issue: Fix all Sphinx reference warnings in the documentation #101100

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📚 Documentation preview 📚: https://cpython-previews--136163.org.readthedocs.build/

[miss-islington-app]

Thanks @sobolevn for the PR, and @hugovk for merging it 🌮🎉.. I'm working now to backport this PR to: 3.13, 3.14.
🐍🍒⛏🤖

[bedevere-app]

GH-136372 is a backport of this pull request to the 3.14 branch.

[bedevere-app]

GH-136373 is a backport of this pull request to the 3.13 branch.

[StanFromIreland]

This will be unnecessary with #136164, should I revert this there?

[hugovk]

Yes please :)