Add a GitHub Actions workflow to run the test suite

.github/workflows/test.yml

@@ -0,0 +1,31 @@
+---
+name: tests
+on: [ push, pull_request ]
+jobs:
+  test:
+    name: Test (Ruby ${{ matrix.ruby }})
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby: [ '3.2', '3.1', '3.0' ]
+    steps:
+      - uses: actions/checkout@v4
+      - name: Set up Ruby ${{ matrix.ruby }}
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - name: RSpec
+        run: bundle exec rspec
+        env:
+          DATABASE_URL: postgres://postgres:secretdb@localhost:25432/event_sourcery_todo_app_test
+    services:
+      postgres:
+        image: postgres
+        env:
+          POSTGRES_DB: event_sourcery_todo_app_test
+          POSTGRES_PASSWORD: secretdb
+        ports:
+          - 25432:5432
+