CI: Update action checkout

Signed-off-by: Daijiro Fukuda <[email protected]>

Author: daipom

.github/workflows/test.yaml

@@ -15,7 +15,7 @@ jobs:
           - macos-latest
     name: Test on ${{ matrix.os }} with Ruby ${{ matrix.ruby }}
     steps:
-      - uses: actions/checkout@v2
+      - uses: actions/checkout@v3
       - name: Set up Ruby
         uses: ruby/setup-ruby@v1
         with: