chore: add test workflow

Author: bethesque

.github/workflows/test.yml

@@ -0,0 +1,23 @@
+name: Test
+
+on: push
+
+jobs:
+  test:
+    runs-on: "ubuntu-latest"
+    continue-on-error: ${{ matrix.experimental }}
+    strategy:
+      fail-fast: false
+      matrix:
+        ruby_version: ["2.2", "2.7"]
+        experimental: [false]
+        include:
+          - ruby_version: "3.0"
+            experimental: true
+    steps:
+      - uses: actions/checkout@v2
+      - uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: ${{ matrix.ruby_version }}
+      - run: "bundle install"
+      - run: "bundle exec rake"