update permissions

add write contents permissions so that we can leave a comment
on the PR

Author: benfred

.github/workflows/check-c-abi.yaml

@@ -88,6 +88,8 @@ jobs:
   check-pr:
     if: github.event_name == 'pull_request' || github.event_name == 'workflow_call'
     runs-on: ubuntu-latest
+    permissions:
+      contents: write
     steps:
       - name: Checkout PR branch
         uses: actions/checkout@v4