[NDR-319] Add read permissions to job

Author: megan-bower4

.github/workflows/automated-pr-validator.yml

@@ -126,6 +126,8 @@ jobs:
   checklist_validator:
     name: Checklist Validation
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
     steps:
     - name: Checkout repository
       uses: actions/checkout@v5