provide memcached for CI tests

Author: onli

.github/workflows/ci.yml

@@ -8,6 +8,7 @@ jobs:
     runs-on: ubuntu-latest
 
     steps:
+      - uses: niden/actions-memcached@v7
       - uses: actions/checkout@v6
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1