Uses ruby/setup-ruby GH action

.github/workflows/build.yml

@@ -9,14 +9,14 @@ jobs:
 
     strategy:
       matrix:
-        ruby: [2.5, 2.6, 2.7, 3.0, 3.1]
+        ruby: [2.5, 2.6, 2.7, '3.0', 3.1]
 
     steps:
     - name: Checkout code
       uses: actions/checkout@v2.4.0
 
     - name: Set up Ruby ${{ matrix.ruby }}
-      uses: actions/setup-ruby@v1.1.3
+      uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}