Merge pull request msyk#109 from matsuo/update-phpstan

Update PHPStan to 2.0

Author: msyk

composer.json

@@ -16,7 +16,7 @@
   },
   "require-dev": {
     "phpunit/phpunit": "*",
-    "phpstan/phpstan": "^1.12"
+    "phpstan/phpstan": "^2.0"
   },
   "autoload": {
     "psr-4": {