Update phpstan/phpstan requirement from ^1.8.11 to ^2.0.1

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/2.0.x/CHANGELOG.md)
- [Commits](phpstan/phpstan@1.8.11...2.0.1)

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

Signed-off-by: dependabot[bot] <[email protected]>

composer.json

@@ -27,7 +27,7 @@
   },
   "require-dev": {
     "squizlabs/php_codesniffer": "3.*",
-    "phpstan/phpstan": "^1.8.11",
+    "phpstan/phpstan": "^2.0.1",
     "phpunit/phpunit": "^11.2",
     "oxid-esales/oxideshop-ce": "dev-b-7.2.x",
     "mikey179/vfsstream": "~1.6.8",