chore(deps): update actions/checkout action to v6 (#57)

Author: renovate[bot]

.github/workflows/build.yml

@@ -34,7 +34,7 @@ jobs:
       BUNDLE_GEMFILE: ${{ matrix.gemfile }}
     steps:
     - name: Checkout Code
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
     - name: Setup Ruby
       uses: ruby/setup-ruby@v1
       with:
@@ -50,7 +50,7 @@ jobs:
     if: ${{ github.ref_name == 'main' && github.event_name != 'pull_request' }}
     steps:
     - name: Checkout Code
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
     - name: Setup Ruby
       uses: ruby/setup-ruby@v1
       with:
@@ -67,7 +67,7 @@ jobs:
     if: ${{ github.ref_name == 'main' && github.event_name != 'pull_request' }}
     steps:
     - name: Checkout Code
-      uses: actions/checkout@v5
+      uses: actions/checkout@v6
     - name: Setup Ruby
       uses: ruby/setup-ruby@v1
       with: