Use ruby_versions.yml

Author: hsbt

.github/workflows/test.yml

@@ -3,14 +3,28 @@ name: test
 on: [push, pull_request]
 
 jobs:
+  ruby-versions:
+    uses: ruby/actions/.github/workflows/ruby_versions.yml@master
+    with:
+      engine: cruby
+      min_version: 2.1
+
   build:
+    needs: ruby-versions
     name: build (${{ matrix.ruby }} / ${{ matrix.os }})
     strategy:
       matrix:
-        ruby: [ '3.0', 2.7, 2.6, 2.1, head, truffleruby-head ]
+        ruby: ${{ fromJson(needs.ruby-versions.outputs.versions) }}
         os: [ ubuntu-latest, macos-latest, windows-latest ]
+        include:
+          - { os: ubuntu-latest, ruby: truffleruby-head }
+          - { os: macos-latest, ruby: truffleruby-head }
         exclude:
-        - { os: windows-latest, ruby: truffleruby-head }
+        - { os: macos-latest, ruby: 2.1 }
+        - { os: macos-latest, ruby: 2.2 }
+        - { os: macos-latest, ruby: 2.3 }
+        - { os: macos-latest, ruby: 2.4 }
+        - { os: macos-latest, ruby: 2.5 }
     runs-on: ${{ matrix.os }}
     steps:
     - name: git config