Update phpstan/phpstan requirement from 2.2.5 to 2.2.6 (#252)

Updates the requirements on [phpstan/phpstan](https://github.com/phpstan/phpstan-phar-composer-source) to permit the latest version.
- [Commits](https://github.com/phpstan/phpstan-phar-composer-source/commits)

---
updated-dependencies:
- dependency-name: phpstan/phpstan
  dependency-version: 2.2.6
  dependency-type: direct:development
...

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Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

composer.json

@@ -34,7 +34,7 @@
         "symfony/phpunit-bridge": "^8.0",
         "symfony/routing": "^5.4 || ^6.0 || ^7.0 || ^8.0",
         "facile-it/facile-coding-standard": "1.5.0",
-        "phpstan/phpstan": "2.2.5",
+        "phpstan/phpstan": "2.2.6",
         "phpstan/extension-installer": "1.4.3",
         "jangregor/phpstan-prophecy": "2.3.0",
         "phpspec/prophecy": "^1.17",