Change type of Fulfillment.OriginAddress to FulfillmentOriginAddress

The Fulfillment.OriginAddress was previously type `Address`, which is a generic address entity used by several address  endpoints. It was not meant to be used as the origin address for a fulfillment. Most properties on that object were always null for the origin address.

ShopifySharp/Entities/Fulfillment.cs

@@ -128,9 +128,9 @@ public class Fulfillment : ShopifyObject
         public string Name { get; set; }
 
         /// <summary>
-        /// The address of the fulfillment location
+        /// The address of the fulfillment location.
         /// </summary>
         [JsonProperty("origin_address")]
-        public Address OriginAddress { get; set; }
+        public FulfillmentOriginAddress OriginAddress { get; set; }
     }
 }