Update .github/workflows/ci.yaml

.github/workflows/ci.yaml

@@ -1,4 +1,4 @@
-on: 
+on:
   push:
   pull_request:
     types: [opened, synchronize]
@@ -8,9 +8,10 @@ jobs:
     name: script/cibuild
     steps:
       - uses: actions/checkout@v2
-      - uses: actions/setup-ruby@v1
+      - uses: ruby/setup-ruby@v1
         with:
           ruby-version: 2.7
+          bundler-cache: true
       - name: build
         run: script/bootstrap
       - name: test