text: Title: Run coverage tests only when source code is modified in PR
  Body: # Brief Description
  
  For PRs that only touch the infrastructure code (e.g. README.md, or `.pre-commit-config.yaml` and the likes), we need not waste resources running coverage. Also, coverage is flaky sometimes.
  
  Exceptions: `.codecov.yml`, `janitor/*`, and `tests/*` ?
  
  Commits into `dev` should still run coverage.