Update permission to write gh-pages (#834)

Author: tpadioleau

.github/workflows/pages.yaml

@@ -137,6 +137,8 @@ jobs:
   pages:
     runs-on: ubuntu-latest
     needs: [docker-build, id_repo]
+    permissions:
+      contents: write
     steps:
       - name: Free Disk Space (Ubuntu)
         uses: jlumbroso/free-disk-space@54081f138730dfa15788a46383842cd2f914a1be  # v1.3.1