Merge branch 'cw/ci-whitespace' into maint-2.39

CI updates.  We probably want a clean-up to move the long shell
script embedded in yaml file into a separate file, but that can
come later.

* cw/ci-whitespace:
  ci (check-whitespace): move to actions/checkout@v3
  ci (check-whitespace): add links to job output
  ci (check-whitespace): suggest fixes for errors