Add tidy as commit message verb

Author: acb-mv

.github/workflows/git-commit-message-style.yml

@@ -28,3 +28,5 @@ jobs:
           allow-one-liners: 'true'
           # This action defaults to 50 char subjects, but 72 is fine.
           max-subject-line-length: '72'
+          # The action's wordlist is a bit short. Add more accepted verbs
+          additional-verbs: 'tidy'