Update phpstan/phpstan requirement from ^1.11 to ^1.11 || ^2.0

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@1.11.0...2.0.3)

---
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": {
         "phlak/coding-standards": "^2.0",
-        "phpstan/phpstan": "^1.11",
+        "phpstan/phpstan": "^1.11 || ^2.0",
         "phpunit/phpunit": "^9.0 || ^10.0",
         "yoast/phpunit-polyfills": "^2.0"
     },