include variants when loading inventory_units in Shipment#to_package
include variants when loading inventory_units in Shipment#to_package

If there are 100 inventory units for a shipment, there were 100 queries for the inventory units' variants. This small alteration reduces the queries to 1.

Antdesk/karpal-spree,Antdesk/karpal-spree,Antdesk/karpal-spree