Grant comment workflow permissions

Only grant the minimal permissions to write a comment on a
pull-request.

Author: willcl-ark

.github/workflows/comment.yml

@@ -8,6 +8,8 @@ on:
 
 jobs:
   comment:
+    permissions:
+      pull-requests: write
     runs-on: ubuntu-latest
     if: >
       github.event.workflow_run.event == 'pull_request' &&