Add basic github action yaml

.github/workflows/ci.yaml

@@ -0,0 +1,34 @@
+name: CI
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+jobs:
+  ci:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby: [3.1, 3.2, 3.3]
+        rails: [61, 70, 71, 72]
+
+        # Rails 7.2 requires ruby 3.1 and higher
+        include:
+          - ruby: "3.0"
+            rails: 61
+          - ruby: "3.0"
+            rails: 70
+          - ruby: "3.0"
+            rails: 71
+    env:
+      BUNDLE_GEMFILE: gemfiles/rails_${{ matrix.rails }}.gemfile
+    steps:
+      - name: checkout code
+        uses: actions/checkout@v4
+      - name: setup Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+      - name: run tests
+        run: bundle exec rake