Use actions/checkout@v3

Author: amatsuda

.github/workflows/ci.yml

@@ -61,7 +61,7 @@ jobs:
       BUNDLE_GEMFILE: ${{ matrix.gemfile }}
 
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with: