Move CI to GitHub Actions (#134)

.github/workflows/ci.yml

@@ -0,0 +1,40 @@
+name: CI
+on: [push, pull_request]
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby: [ 2.6, 2.7 ]
+        rails: [ '5.0', '5.1', '5.2', '6.0', '6.1' ]
+        include:
+          - ruby: '3.0'
+            rails: '6.0'
+          - ruby: '3.0'
+            rails: '6.1'
+          - ruby: head
+            rails: '6.0'
+          - ruby: head
+            rails: '6.1'
+          - ruby: truffleruby
+            rails: '6.0'
+          - ruby: truffleruby
+            rails: '6.1'
+
+    env:
+      BUNDLE_GEMFILE: ${{ github.workspace }}/gemfiles/rails_${{ matrix.rails }}.gemfile
+
+    steps:
+      - uses: actions/checkout@v2
+
+      - name: Set up Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby }}
+          bundler-cache: true
+
+      - name: Run tests
+        run: bundle exec rake test
+        continue-on-error: ${{ matrix.ruby == 'head' || matrix.ruby == 'truffleruby' }}
+        timeout-minutes: 3