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

Updates the requirements on [phpstan/phpstan-phpunit](https://github.com/phpstan/phpstan-phpunit) to permit the latest version.
- [Release notes](https://github.com/phpstan/phpstan-phpunit/releases)
- [Commits](phpstan/phpstan-phpunit@1.3.15...1.3.16)

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

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

composer.json

@@ -53,7 +53,7 @@
         "friendsofphp/php-cs-fixer": "dev-master",
         "phpunit/phpunit": "^10.5",
         "phpstan/phpstan": "^1.10.59",
-        "phpstan/phpstan-phpunit": "^1.3.15",
+        "phpstan/phpstan-phpunit": "^1.3.16",
         "phpstan/extension-installer": "^1.3.1",
         "phpstan/phpstan-deprecation-rules": "^1.1.4",
         "phpstan/phpstan-strict-rules": "^1.5.2",