ci: set PT 2.2 as stable latest

[Borda]

What does this PR do?

Follow the final PT 2.2 release, not using RC any more...

Before submitting

• Was this discussed/agreed via a Github issue? (no need for typos and docs improvements)
• Did you read the contributor guideline, Pull Request section?
• Did you make sure to update the docs?
• Did you write any new necessary tests?

PR review

Anyone in the community is free to review the PR once the tests have passed.
If we didn't discuss your PR in Github issues there's a high chance it will not be merged.

Did you have fun?

Make sure you had fun coding 🙃

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📚 Documentation preview 📚: https://torchmetrics--2352.org.readthedocs.build/en/2352/

[codecov]

Codecov Report

Merging #2352 (46f06c2) into master (0aafdc9) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #2352   +/-   ##
======================================
  Coverage      69%     69%           
======================================
  Files         303     303           
  Lines       17058   17058           
======================================
  Hits        11760   11760           
  Misses       5298    5298