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/11.5.0/ChangeLog-11.5.md)
- [Commits](sebastianbergmann/phpunit@9.6.0...11.5.0)

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

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

Author: dependabot[bot]

composer.json

@@ -20,7 +20,7 @@
         "phpstan/extension-installer": "^1.4",
         "phpstan/phpstan": "^1.12",
         "phpstan/phpstan-deprecation-rules": "^1.2",
-        "phpunit/phpunit": "^9.6",
+        "phpunit/phpunit": "^11.5",
         "symfony/var-dumper": "^5.3",
         "thecodingmachine/phpstan-safe-rule": "^1.2",
         "tomasvotruba/cognitive-complexity": "0.2.3",