update

cmd/cart/checkout_builder.go

@@ -65,7 +65,7 @@ func BuildCheckoutOrderPayload(grain *cart.CartGrain, meta *CheckoutMeta) ([]byt
 			Type:           "physical",
 			Reference:      it.Sku,
 			Name:           it.Meta.Name,
-			Quantity:       it.Quantity,
+			Quantity:       int(it.Quantity),
 			UnitPrice:      int(it.Price.IncVat),
 			TaxRate:        it.Tax, // TODO: derive if variable tax rates are introduced
 			QuantityUnit:   "st",