Add variant association in ransack whitelist
Add variant association in ransack whitelist

Ransack uses variant association to search name and SKU related to the StockItem, for example, in Spree::Api::V1::StockItem ransack search.
Without this setting of whitelisted_ransackable_associations, the search form in Stock Transfers does not work.
maybii/spree,maybii/spree,maybii/spree,maybii/spree