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

Updates the requirements on [phpstan/phpstan](https://github.com/phpstan/phpstan) to permit the latest version.
- [Release notes](https://github.com/phpstan/phpstan/releases)
- [Changelog](https://github.com/phpstan/phpstan/blob/1.11.x/CHANGELOG.md)
- [Commits](phpstan/phpstan@1.10.14...1.10.15)

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

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

composer.json

@@ -48,7 +48,7 @@
         "laravel/legacy-factories": "^1.0",
         "mfn/php-cs-fixer-config": "^2",
         "mockery/mockery": "^1.2",
-        "phpstan/phpstan": "1.10.14",
+        "phpstan/phpstan": "1.10.15",
         "nunomaduro/larastan": "2.6.0",
         "orchestra/testbench": "4.0.*|5.0.*|^6.0|^7.0|^8.0",
         "phpunit/phpunit": "~7.0|~8.0|^9",