CI: trigger on relevant files

[pjonsson]

Without this, updates to docker-compose.yml
and pre-commit PRs cannot be merged without
overriding the CI.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 38.60%. Comparing base (e370c4f) to head (77b4bcf).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #224   +/-   ##
=======================================
  Coverage   38.60%   38.60%           
=======================================
  Files           7        7           
  Lines         891      891           
  Branches       99       99           
=======================================
  Hits          344      344           
  Misses        508      508           
  Partials       39       39           

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