ci: only report pgp lint on error

Author: kanru

.github/workflows/authenticate-commits.yml

@@ -14,6 +14,8 @@ jobs:
     steps:
       - name: Authenticating commits
         uses: sequoia-pgp/authenticate-commits@v1
+        env:
+          COMMENT: on-error
         with:
           # To reduce the workflow's verbosity, use 'on-error'
           # to only post a comment when an error occurs, or 'never' to