bump required PHPStan

Author: spawnia

composer.json

@@ -21,7 +21,7 @@
     "ergebnis/composer-normalize": "^2.13",
     "mll-lab/php-cs-fixer-config": "^5",
     "phpstan/extension-installer": "^1",
-    "phpstan/phpstan": "^1 || ^2"
+    "phpstan/phpstan": "^1.9.3 || ^2"
   },
   "autoload": {
     "files": [