Bump stan

Author: TamasSzigeti

composer.json

@@ -25,7 +25,7 @@
   "require-dev": {
     "phpunit/phpunit": "^8.4.1",
     "mouf/picotainer": "^1.1",
-    "phpstan/phpstan": "^0.12.14",
+    "phpstan/phpstan": "^0.12.99",
     "php-coveralls/php-coveralls": "^2.1.0",
     "symfony/translation": "^4",
     "doctrine/coding-standard": "^9.0"