composer(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@1.2.0...1.3.15)

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

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

Author: dependabot[bot]

composer.json

@@ -32,7 +32,7 @@
         "illuminate/support": "^10",
         "league/uri": "~6.7 || ~6.8",
         "phpstan/extension-installer": "^1.2",
-        "phpstan/phpstan-phpunit": "^1.2"
+        "phpstan/phpstan-phpunit": "^1.3"
     },
     "require-dev": {
         "dg/bypass-finals": "^1.4",