Update phpunit/phpunit requirement from ^9.0 to ^9.0 || ^11.0

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/11.4.4/ChangeLog-11.4.md)
- [Commits](sebastianbergmann/phpunit@9.0.0...11.4.4)

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

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

composer.json

@@ -27,7 +27,7 @@
         "php": ">=8.2",
         "phlak/coding-standards": "^3.0",
         "phpstan/phpstan": "^2.0",
-        "phpunit/phpunit": "^9.0",
+        "phpunit/phpunit": "^9.0 || ^11.0",
         "psy/psysh": "^0.12.5",
         "symfony/var-dumper": "^6.0",
         "yoast/phpunit-polyfills": "^3.0"