Update composer.json

Author: dostrog

composer.json

@@ -11,7 +11,7 @@
     ],
     "require": {
         "laravel/framework": "5.5.* || 5.6.*",
-        "phpstan/phpstan": "^0.11.2"
+        "phpstan/phpstan": "0.11.2"
     },
     "require-dev": {
         "phpunit/phpunit": "^6.5.2"