Add PHPStan to require-dev dependencies

PHPStan has been added to the development dependencies in `composer.json` to enhance static code analysis. This will help identify potential issues and improve code quality during development.

Author: mvd81

composer.json

@@ -19,6 +19,7 @@
     },
     "require-dev": {
         "orchestra/testbench": "^7.0",
+        "phpstan/phpstan": "^1.10",
         "phpunit/phpunit": "^9.5"
     },
     "autoload": {