Add explicit write permissions to workflow

Author: sd109

.github/workflows/test-pr.yml

@@ -37,6 +37,10 @@ jobs:
     with:
       ref: ${{ github.sha }}
     secrets: inherit
+    permissions:
+      # Explicit permissions are required for
+      # PRs created by dependabot user
+      contents: write
 
   chart_validation:
     needs: [publish_images]