Add workflow to lint YAML files

[make-github-pseudonymous-again]

Together with #967, fixes #962.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.86%. Comparing base (60ca4dd) to head (5a9a577).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #968      +/-   ##
==========================================
- Coverage   66.12%   65.86%   -0.27%     
==========================================
  Files         715      715              
  Lines        9893     9893              
  Branches     1346     1346              
==========================================
- Hits         6542     6516      -26     
- Misses       2888     2918      +30     
+ Partials      463      459       -4     

Flag	Coverage Δ
client	46.23% <ø> (-0.27%)	⬇️
server	61.87% <ø> (ø)
test	71.97% <ø> (+0.01%)	⬆️
test-app	53.70% <ø> (-0.32%)	⬇️

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[github-advanced-security]

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