Update phpstan/phpstan requirement from 1.11.10 to 1.12.1

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/1.12.x/CHANGELOG.md)
- [Commits](phpstan/phpstan@1.11.10...1.12.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

composer.json

@@ -40,7 +40,7 @@
     "require-dev": {
         "matthiasnoback/symfony-dependency-injection-test": "^6.0",
         "phpspec/phpspec": "^7.0",
-        "phpstan/phpstan": "1.11.10",
+        "phpstan/phpstan": "1.12.1",
         "phpstan/phpstan-phpunit": "1.4.0",
         "phpstan/phpstan-webmozart-assert": "1.2.9",
         "phpunit/phpunit": "^10.5",