Require PHPStan 1.9

Author: MidnightDesign

composer.json

@@ -7,7 +7,7 @@
     "require-dev": {
         "infection/infection": "^0.26.13",
         "phpstan/extension-installer": "^1.1",
-        "phpstan/phpstan": "^1.8",
+        "phpstan/phpstan": "^1.9",
         "phpstan/phpstan-strict-rules": "^1.3",
         "phpunit/phpunit": "^9.5",
         "slevomat/coding-standard": "^8.1",