chore: Update old Optional syntax to use new type | None syntax

[ToothyDev]

This will make None clickable in the docs and lead to the python docs

Summary

This PR updates the "old" Optional[...] syntax to use the new type | None syntax, primarily affecting docstrings.

Information

• This PR fixes an issue.
• This PR adds something new (e.g. new method or parameters).
• This PR is a breaking change (e.g. methods or parameters removed/renamed).
• This PR is not a code change (e.g. documentation, README, typehinting,
  examples, ...).
• Non-breaking code change that doesn't really add or remove anything :)

Checklist

• I have searched the open pull requests for duplicates.
• If code changes were made then they have been tested.
  • I have updated the documentation to reflect the changes.
• If type: ignore comments were used, a comment is also left explaining why.
• I have updated the changelog to include these changes.
• I have read the Contributing Guidelines.
• AI Usage has been disclosed.
  • If AI has been used, I understand fully what the code does

[pycord-app]

Thanks for opening this pull request!
Please make sure you have read the Contributing Guidelines and Code of Conduct.

This pull request can be checked-out with:

git fetch origin pull/3407/head:pr-3407
git checkout pr-3407

This pull request can be installed with:

pip install git+https://github.com/Pycord-Development/pycord@refs/pull/3407/head

[vmphase]

This is a disaster to review with some many changes done.
All problems tend to be CTRL + SHIFT + F global replace because they're repetitive.