ghcr test with caching

.github/workflows/docker_ci.yml

@@ -34,10 +34,18 @@ jobs:
           # https://github.com/docker/build-push-action?tab=readme-ov-file#git-context
           context: "{{defaultContext}}:backend"
           file: ./Dockerfile
-          tags: ghcr.io/${{ github.repository }}/backend:v9.9.11
+          tags: ghcr.io/${{ github.repository }}/backend:v9.9.12
           cache-from: type=gha
           cache-to: type=gha,mode=max
 
+      - uses: actions/delete-package-versions@v5
+        with:
+          # TODO: Confirm the package name needed
+          package-name: ghcr.io/${{ github.repository}}/backend
+          package-type: 'container'
+          min-versions-to-keep: 3
+          num-old-versions-to-delete: 1
+
   # lint-backend-code:
   #   name: Lint and test backend python code
   #   runs-on: ubuntu-latest