CI: Fix weekly cache cleanup job (#54067)

Author: mroeschke

.github/workflows/cache-cleanup-weekly.yml

@@ -7,6 +7,9 @@ on:
 jobs:
   cleanup:
     runs-on: ubuntu-latest
+    if: github.repository_owner == 'pandas-dev'
+    permissions:
+      actions: write
     steps:
       - name: Clean Cache
         run: |