Updated checkout action [skip ci]

Author: ankane

.github/workflows/build.yml

@@ -14,7 +14,7 @@ jobs:
           - ruby: "3.0"
             os: macos-latest
     steps:
-      - uses: actions/checkout@v3
+      - uses: actions/checkout@v4
       - uses: ruby/setup-ruby@v1
         with:
           ruby-version: ${{ matrix.ruby }}