Update phpunit/phpunit requirement from ^9.6 to ^11.5

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/11.5.3/ChangeLog-11.5.md)
- [Commits](sebastianbergmann/phpunit@9.6.0...11.5.3)

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

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

Author: dependabot[bot]

composer.json

@@ -14,7 +14,7 @@
         "yiisoft/yii2": "*"
     },
     "require-dev": {
-        "phpunit/phpunit": "^9.6"
+        "phpunit/phpunit": "^11.5"
     },
     "repositories": [
     {