Update app/code/Magento/VaultGraphQl/Model/Resolver/PaymentTokens.php

Co-authored-by: Dmytro Cheshun <d.cheshun@atwix.com>

Author: Usik2203

app/code/Magento/VaultGraphQl/Model/Resolver/PaymentTokens.php

@@ -54,7 +54,7 @@ class PaymentTokens implements ResolverInterface
      */
     public function __construct(
         PaymentTokenManagement $paymentTokenManagement,
-        JsonSerializer $serializer
+        JsonSerializer $serializer = null
     ) {
         $this->paymentTokenManagement = $paymentTokenManagement;
         $this->serializer = $serializer;