Setup review-ready label synchronization (#333)

Committed via https://github.com/asottile/all-repos

Author: asvetlov

.github/workflows/review-label.yml

@@ -27,6 +27,8 @@ jobs:
     timeout-minutes: 5
     env:
       GH_TOKEN: ${{ github.token }}
+    permissions:
+      pull-requests: write
     steps:
     - name: Ensure label exists
       run: |