Payment specs fixed

lib/yookassa/entity/payment.rb

@@ -42,7 +42,7 @@ module Yookassa
 
       # payment_method [object, optional]
       # Payment method  used for this payment.
-      attribute? :payment_method, Entity::PaymentMethod
+      attribute? :payment_method, Entity::PaymentMethods
 
       # captured_at [datetime, optional]
       # Time of payment capture, based on UTC and specified in the ISO 8601 format. "2018-07-18T10:51:18.139Z"