Use minimum required permissions for GitHub workflows

This reduces the attack surface if the workflows are ever compromised.

.github/workflows/no-response.yml

@@ -9,6 +9,10 @@ on:
     # Run daily at midnight.
     - cron: '0 0 * * *'
 
+permissions:
+  issues: write
+  pull-requests: write
+
 jobs:
   noResponse:
     runs-on: ubuntu-latest