Update LocalType to nullable

Author: armando-rodriguez-cko

src/CheckoutSdk/Payments/Links/PaymentLinkRequest.cs

@@ -60,7 +60,7 @@ public class PaymentLinkRequest
 
         public string ReturnUrl { get; set; }
 
-        public LocaleType Locale { get; set; }
+        public LocaleType? Locale { get; set; }
 
         public bool? Capture { get; set; }
 
@@ -70,4 +70,4 @@ public class PaymentLinkRequest
 
         public PaymentMethodConfiguration PaymentMethodConfiguration { get; set; }
     }
-}
+}