[BUGFIX] Fix wrong check for waitlist moval

The client uses the backend to add additional registrations. Because of this, the count of free places becomes not 0 but negative. because of the wrong check this leads to the bug that *all* valid waiting list registrations are moved from the waiting list to the regular list

Classes/Service/RegistrationService.php

@@ -351,7 +351,7 @@ public function moveUpWaitlistRegistrations(Event $event, array $settings): void
     {
         // Early return if move up not enabled, no registrations on waitlist or no free places left
         if (!$event->getEnableWaitlistMoveup() || $event->getRegistrationsWaitlist()->count() === 0 ||
-            $event->getFreePlaces() === 0
+            $event->getFreePlaces() <= 0
         ) {
             return;
         }