Run tests with different Ruby versions, 2.7 to 3.3.

.github/workflows/test-app.yml

@@ -1,17 +1,19 @@
 name: Ruby tests
 
-on: [push]
+on: [push, pull_request]
 
 jobs:
   test:
+    strategy:
+      matrix:
+        ruby: ['2.7', '3.0', '3.1', '3.2', '3.3']
     runs-on: ubuntu-latest
     steps:
-    - uses: actions/checkout@v2
+    - uses: actions/checkout@v4
     - name: Set up Ruby
       uses: ruby/setup-ruby@v1
       with:
-        ruby-version: 2.7
-    - name: Install dependencies (bundle)
-      run: bundle install
+        ruby-version: ${{ matrix.ruby }}
+        bundler-cache: true
     - name: Run tests
-      run: rake test
+      run: bundle exec rake test