ci: update with Torch released 2.6

[Borda]

What does this PR do?

update testing matrix after released 2.6

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--2922.org.readthedocs.build/en/2922/

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70%. Comparing base (19c0601) to head (dc32b89).
Report is 1 commits behind head on master.

Additional details and impacted files

@@           Coverage Diff           @@
##           master   #2922    +/-   ##
=======================================
- Coverage      70%     70%    -0%     
=======================================
  Files         346     332    -14     
  Lines       19172   18996   -176     
=======================================
- Hits        13428   13253   -175     
+ Misses       5744    5743     -1