check php syntax on all supported versions

.github/workflows/php-check-syntax.yml

@@ -0,0 +1,20 @@
+name: Check PHP syntax
+
+on: [ push, pull_request ]
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        php-versions: ['7.3', '7.4', '8.0', '8.1', '8.2', '8.3', 'highest']
+    steps:
+      - name: Setup PHP
+        uses: shivammathur/setup-php@v2
+        with:
+          php-version: ${{ matrix.php-versions }}
+
+      - name: checkout repo
+        uses: actions/checkout@v3
+
+      - run: composer run check-syntax