composer(deps-dev): update phpstan/phpstan requirement

Updates the requirements on [phpstan/phpstan](https://github.com/phpstan/phpstan) to permit the latest version.
- [Release notes](https://github.com/phpstan/phpstan/releases)
- [Changelog](https://github.com/phpstan/phpstan/blob/2.1.x/CHANGELOG.md)
- [Commits](phpstan/phpstan@2.1.0...2.1.1)

---
updated-dependencies:
- dependency-name: phpstan/phpstan
  dependency-type: direct:development
...

Signed-off-by: dependabot[bot] <support@github.com>

composer.json

@@ -38,7 +38,7 @@
     "mimmi20/ua-result": "^10.0.1",
     "nikic/php-parser": "^5.4.0",
     "phpstan/extension-installer": "^1.4.3",
-    "phpstan/phpstan": "^2.1.0",
+    "phpstan/phpstan": "^2.1.1",
     "phpstan/phpstan-deprecation-rules": "^2.0.1",
     "phpstan/phpstan-phpunit": "^2.0.3",
     "phpunit/phpunit": "^11.5.2",