Update PHPStan to 1.0

Author: mmoll

composer.json

@@ -23,8 +23,8 @@
     },
     "require-dev": {
         "phan/phan": "^5.1.0",
-        "phpstan/phpstan": "^0.12.58",
-        "phpstan/phpstan-strict-rules": "^0.12.4",
+        "phpstan/phpstan": "^1.0.0",
+        "phpstan/phpstan-strict-rules": "^1.0.0",
         "phpunit/phpunit": "^7.0",
         "psalm/plugin-phpunit": "^0.16.1",
         "vimeo/psalm": "^4.5.2"