Update dependency phpstan/phpstan to v2.1.40 (#35)

Author: rinus

composer.json

@@ -38,7 +38,7 @@
     "php": "8.2 - 8.5"
   },
   "require-dev": {
-    "phpstan/phpstan": "2.1.39",
+    "phpstan/phpstan": "2.1.40",
     "phpunit/phpunit": "11.5.50",
     "squizlabs/php_codesniffer": "4.0.1",
     "friendsofphp/php-cs-fixer": "3.94.2"