Add typing for FixtureRequest.param

[nipunn1313]

For now, mark it as Any until #8073 is solved

Closes #9514

• [N/A] Include documentation when adding new features.
• Include new tests or update existing tests when applicable.
  (added a type annotation in the file to prove it works)
• Allow maintainers to push and squash when merging my commits. Please uncheck this if you prefer to squash the commits yourself.
• Create a new changelog file in the changelog folder, with a name like <ISSUE NUMBER>.<TYPE>.rst. See changelog/README.rst for details.
• Add yourself to AUTHORS in alphabetical order.

[nicoddemus]

Failures in 3.11 can be ignored as they have been fixed by #10132.

[nicoddemus]

LGTM, thanks!

I will leave to @bluetech to given the final approve/merge. 😁

[RonnyPfannschmidt]

I wonder how tricky it would actually be to have the requests class getattr return a bound generic of the subrequest

[bluetech]

Seems fine to me as a stop gap.

I added a suggestion for a comment that makes the situation clear, for when we properly tackle this in the future.

[nicoddemus]

Thanks @nipunn1313!