Update phpunit/phpunit requirement from ^9.6 to ^11.4

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/11.4.3/ChangeLog-11.4.md)
- [Commits](sebastianbergmann/phpunit@9.6.0...11.4.3)

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

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

composer.json

@@ -23,7 +23,7 @@
         "php-coveralls/php-coveralls": "^2.7",
         "phpstan/phpstan": "^1.10",
         "phpstan/phpstan-strict-rules": "^1.5",
-        "phpunit/phpunit": "^9.6",
+        "phpunit/phpunit": "^11.4",
         "rector/rector": "^1.0.3",
         "squizlabs/php_codesniffer": "^3.8"
     },