tools(deps-dev): Update phpunit/phpunit requirement in /tools/phpunit (#378)

Updates the requirements on [phpunit/phpunit](https://github.com/sebastianbergmann/phpunit) to permit the latest version.
- [Changelog](https://github.com/sebastianbergmann/phpunit/blob/10.5.1/ChangeLog-10.5.md)
- [Commits](sebastianbergmann/phpunit@10.4.2...10.5.1)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

tools/phpunit/composer.json

@@ -6,7 +6,7 @@
         "php": "^8.1"
     },
     "require-dev": {
-        "phpunit/phpunit": "10.4.2",
+        "phpunit/phpunit": "10.5.1",
         "roave/security-advisories": "dev-latest"
     },
     "prefer-stable": true,