Use ruby/setup-ruby instead of actions/setup-ruby

Author: hsbt

.github/workflows/macos.yml

@@ -4,14 +4,15 @@ on: [push]
 
 jobs:
   build:
-    runs-on: ubuntu-latest
+    runs-on: ${{ matrix.os }}
     strategy:
       matrix:
-        ruby: [ '2.6.x', '2.5.x', '2.4.x' ]
+        os: [ 'ubuntu-latest', 'macos-latest', 'windows-latest' ]
+        ruby: [ 'head', '2.7', '2.6', '2.5', '2.4' ]
     steps:
     - uses: actions/checkout@master
     - name: Set up Ruby
-      uses: actions/setup-ruby@v1
+      uses: ruby/setup-ruby@v1
       with:
         ruby-version: ${{ matrix.ruby }}
     - name: Install dependencies