Update dependency phpstan/phpstan to v2.1.50 (#1899)

* Update dependency phpstan/phpstan to v2.1.50

* Fix PHPStan error with ReflectionAttribute::newInstance() return type

PHPStan 2.1.50 no longer infers the generic type parameter of
ReflectionAttribute when getAttributes() is called on a union type
(ReflectionClassConstant|ReflectionClass), resulting in object instead
of the expected Description type.

🤖 Generated with Claude Code

---------

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>
Co-authored-by: Benedikt Franke <benedikt.franke@mll.com>

Author: renovate[bot]

composer.json

@@ -23,7 +23,7 @@
     "nyholm/psr7": "^1.5",
     "phpbench/phpbench": "^1.2",
     "phpstan/extension-installer": "^1.1",
-    "phpstan/phpstan": "2.1.46",
+    "phpstan/phpstan": "2.1.50",
     "phpstan/phpstan-phpunit": "2.0.16",
     "phpstan/phpstan-strict-rules": "2.0.10",
     "phpunit/phpunit": "^9.5 || ^10.5.21 || ^11",

src/Type/Definition/PhpEnumType.php

@@ -108,7 +108,10 @@ protected function extractDescription(\ReflectionClassConstant|\ReflectionClass
         $attributes = $reflection->getAttributes(Description::class);
 
         if (count($attributes) === 1) {
-            return $attributes[0]->newInstance()->description;
+            $description = $attributes[0]->newInstance();
+            assert($description instanceof Description);
+
+            return $description->description;
         }
 
         if (count($attributes) > 1) {