ci: add missing labeler job

[Borda]

What does this PR do?

Seems we had the config but missing job so not much happened...

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?

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📚 Documentation preview 📚: https://torchmetrics--2038.org.readthedocs.build/en/2038/

[codecov]

Codecov Report

Merging #2038 (3a99386) into master (66f1859) will not change coverage.
The diff coverage is n/a.

Additional details and impacted files

@@          Coverage Diff           @@
##           master   #2038   +/-   ##
======================================
  Coverage      87%     87%           
======================================
  Files         279     279           
  Lines       15814   15814           
======================================
  Hits        13718   13718           
  Misses       2096    2096