Update phpunit/phpunit requirement from ^10.3.2 to ^11.3.6

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/11.3.6/ChangeLog-11.3.md)
- [Commits](sebastianbergmann/phpunit@10.3.2...11.3.6)

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

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

composer.json

@@ -20,7 +20,7 @@
         "nesbot/carbon": "^3.6"
     },
     "require-dev": {
-        "phpunit/phpunit": "^10.3.2"
+        "phpunit/phpunit": "^11.3.6"
     },
     "autoload": {
         "psr-4": {