Update phpunit/phpunit requirement from ^11.5 to ^11.5 || ^12.0

Updates the requirements on [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) to permit the latest version.
- [Release notes](https://github.com/sebastianbergmann/phpunit/releases)
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/12.0.2/ChangeLog-12.0.md)
- [Commits](sebastianbergmann/phpunit@11.5.0...12.0.2)

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

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

composer.json

@@ -20,7 +20,7 @@
     "kununu/scripts": ">=5.1",
     "phpstan/phpstan": "^2.1",
     "phpstan/phpstan-phpunit": "^2.0",
-    "phpunit/phpunit": "^11.5",
+    "phpunit/phpunit": "^11.5 || ^12.0",
     "rector/rector": "^2.0"
   },
   "autoload": {