Update checkout Github Action to v4

Author: honsq90

.github/workflows/ci.yml

@@ -17,7 +17,7 @@ jobs:
         ruby: [3.2]
     steps:
     - name: Check out code
-      uses: actions/checkout@v2
+      uses: actions/checkout@v4
     - name: Set up Ruby ${{ matrix.ruby }}
       uses: ruby/setup-ruby@v1
       with: