[BUG] Deprecation / ErrorException due to http-foundation 5.1 deprecation

[huelsmc]

CKFinder causes an Exception due to the fact that it still uses JsonResponse::create instead of "new JsonResponse".

Uncaught PHP Exception ErrorException: "Since symfony/http-foundation 5.1: The "Symfony\Component\HttpFoundation\JsonResponse::create()" method is deprecated, use "new CKSource\CKFinder\Response\JsonResponse()" instead."

The deprecated function is used in CKFinder.php itself as well as in the ExceptionHandler (other Classes might be affected as well and it seems not only the JsonResponses are using the outdated function.)

Besides this your versioning is inconsistent:
const VERSION = '3.5.1.2'; does not match the packages name 3.5.2.1