test different ruby versions & engines

.github/workflows/ruby.yml

@@ -8,6 +8,9 @@ on:
 
 jobs:
   test:
+    strategy:
+      matrix:
+        ruby: [2.5, 2.6, 2.7, jruby, truffleruby]
     runs-on: ubuntu-latest
     steps:
     - name: Install dependencies
@@ -16,6 +19,8 @@ jobs:
     - uses: actions/checkout@v2
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
+      with:
+        ruby-version: ${{ matrix.ruby }}
     - name: Install dependencies
       run: bundle install
     - name: Run tests