Potential fix for code scanning alert no. 46: Workflow does not contain permissions

Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>

Author: Janice-shi

.github/workflows/cleanup-caches.yml

@@ -7,6 +7,9 @@ on:
 jobs:
   cleanup:
     runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      actions: write
     steps:
       - name: Check out code
         uses: actions/checkout@v3