feat: update voucher purchase urls to match established patterns

src/Controller/Voucher/Step3Controller.php

@@ -39,7 +39,7 @@ class Step3Controller extends AbstractVoucherPurchaseController
         parent::__construct($sessionManager, $thumbnailResolver);
     }
 
-    #[Route('/gutschein/uebersicht', name: 'app_voucher_step_3')]
+    #[Route('/vouchers/create/confirmation', name: 'app_voucher_step_3')]
     public function index(Request $request): Response
     {
         $dto = $this->sessionManager->find($request);