Update phpunit/phpunit requirement from ^10.0 to ^11.3

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/11.3.0/ChangeLog-11.3.md)
- [Commits](sebastianbergmann/phpunit@10.0.0...11.3.0)

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

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

composer.json

@@ -14,7 +14,7 @@
         "postal/postal": "^2.0.1"
     },
     "require-dev": {
-        "phpunit/phpunit": "^10.0",
+        "phpunit/phpunit": "^11.3",
         "orchestra/testbench": "^8.0|^9.0",
         "nunomaduro/larastan": "^2.0"
     },