Update phpunit/phpunit requirement from ^9.6.29 to ^13.1.13

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/13.1.13/ChangeLog-13.1.md)
- [Commits](sebastianbergmann/phpunit@9.6.29...13.1.13)

---
updated-dependencies:
- dependency-name: phpunit/phpunit
  dependency-version: 13.1.13
  dependency-type: direct:development
...

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

Author: dependabot[bot]

composer.json

@@ -36,7 +36,7 @@
     "require-dev": {
         "bamarni/composer-bin-plugin": "^1.8.3",
         "maglnet/composer-require-checker": "^4.4",
-        "phpunit/phpunit": "^9.6.29",
+        "phpunit/phpunit": "^13.1.13",
         "rector/rector": "^2.1.7",
         "spatie/phpunit-watcher": "^1.23.6",
         "yiisoft/di": "^1.2.1"