chore(deps-dev): update phpunit/phpunit requirement

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/11.2.9/ChangeLog-11.2.md)
- [Commits](sebastianbergmann/phpunit@8.5.27...11.2.9)

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

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

composer.json

@@ -16,7 +16,7 @@
     "psr/http-client": "^1.0.1"
   },
   "require-dev": {
-    "phpunit/phpunit": "^8.5.27",
+    "phpunit/phpunit": "^11.2.9",
     "squizlabs/php_codesniffer": "~3.7",
     "guzzlehttp/guzzle": "^7.0.1",
     "guzzlehttp/psr7": "^2.0.0"