Run tests on PR

.github/workflows/ci.yml

@@ -0,0 +1,20 @@
+name: CI
+
+on:
+  push:
+  pull_request_target:
+    types: 
+      - opened
+      - synchronize
+
+jobs:
+  build-test:
+    runs-on: ubuntu-latest
+
+    steps:
+    - uses: actions/checkout@v3
+    - uses: php-actions/composer@v6
+    - uses: php-actions/phpunit@v3
+    - name: PHPUnit tests
+      run: echo "./vendor/bin/phpunit"
+