Enhance PHP workflow with static analysis and style checks

Added PHPStan and code style check to workflow.

.github/workflows/php.yml

@@ -32,8 +32,11 @@ jobs:
     - name: Install dependencies
       run: composer install --prefer-dist --no-progress
 
-    # Add a test script to composer.json, for instance: "test": "vendor/bin/phpunit"
-    # Docs: https://getcomposer.org/doc/articles/scripts.md
+    - name: PHPStan
+      run: composer phpstan
 
-    # - name: Run test suite
-    #   run: composer run-script test
+    - name: Code style check
+      run: composer cs-check
+
+    - name: Tests
+      run: composer test