req: lift pyYAML version freeze

[Borda]

Before submitting

• Was this discussed/approved via a Github issue? (no need for typos and docs improvements)
• Did you make sure to update the docs?
• Did you write any new necessary tests?

What does this PR do?

Addressing Lightning-AI/pytorch-lightning#20111

The conflict is caused by:
    The user requested PyYAML<5.4
    lightning 2.4.0.dev0 depends on PyYAML<6.1.0 and >=5.4

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 🙃

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 70%. Comparing base (d499638) to head (bde05f2).

Additional details and impacted files

@@         Coverage Diff         @@
##           main   #340   +/-   ##
===================================
  Coverage    70%    70%           
===================================
  Files         2      2           
  Lines       416    416           
===================================
  Hits        291    291           
  Misses      125    125