Update phpstan/phpstan requirement from 2.0.3 to 2.0.4 (#290)

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/2.1.x/CHANGELOG.md)
- [Commits](phpstan/phpstan@2.0.3...2.0.4)

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

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

composer.json

@@ -43,7 +43,7 @@
         "phpspec/prophecy": "^1.20",
         "phpspec/prophecy-phpunit": "^2.3.0",
         "phpstan/extension-installer": "^1.0",
-        "phpstan/phpstan": "2.0.3",
+        "phpstan/phpstan": "2.0.4",
         "phpstan/phpstan-phpunit": "^2.0",
         "phpunit/php-invoker": "^4.0||^5.0",
         "psalm/plugin-phpunit": "^0.19",