Use Github Actions

.github/workflows/main.yml

@@ -0,0 +1,29 @@
+name: CI
+
+on: [push, pull_request]
+
+jobs:
+  tests:
+    runs-on: ubuntu-latest
+
+    strategy:
+      matrix:
+        php: [7.1, 7.2, 7.3, 7.4, 8.0]
+
+    steps:
+    - name: Checkout code
+      uses: actions/checkout@v2
+
+    - name: Setup PHP
+      uses: shivammathur/setup-php@v2
+      with:
+        php-version: ${{ matrix.php }}
+
+    - name: Validate composer.json
+      run: composer validate
+
+    - name: Install dependencies
+      run: composer update --prefer-dist --no-progress --no-interaction
+
+    - name: Run test suite
+      run: php vendor/bin/phpunit