Update bitexpert/phpstan-magento requirement from ^0.25.0 to ^0.28.0

Updates the requirements on [bitexpert/phpstan-magento](https://github.com/bitExpert/phpstan-magento) to permit the latest version.
- [Release notes](https://github.com/bitExpert/phpstan-magento/releases)
- [Changelog](https://github.com/bitExpert/phpstan-magento/blob/master/CHANGELOG.md)
- [Commits](bitExpert/phpstan-magento@v0.25.0...v0.28.0)

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

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

composer.json

@@ -27,7 +27,7 @@
   },
   "require-dev": {
     "bitexpert/captainhook-infection": "^0.6.0",
-    "bitexpert/phpstan-magento": "^0.25.0",
+    "bitexpert/phpstan-magento": "^0.28.0",
     "captainhook/captainhook": "^5.10.8",
     "captainhook/plugin-composer": "^5.3.3",
     "infection/infection": "0.22.0|^0.26.6",