Remove temporary PHPStan for testing.

Author: johnbillion

composer.json

@@ -14,7 +14,6 @@
     "require-dev": {
         "php": "~7.3 || ~8.0",
         "phpdocumentor/reflection-docblock": "^5.3",
-        "phpstan/phpstan": "^1.2",
         "php-stubs/generator": "^0.8.0",
         "nikic/php-parser": "< 4.12.0"
     },