Changes to Get discounted products sorted by discount percentage

for the query request parameter currency, default value SGD was removed

removed the enum value MY from the query request parameter country_code

removed the enum value SG from the query request parameter country_code

removed the enum value TH from the query request parameter country_code

removed the enum value US from the query request parameter country_code

removed the enum value VN from the query request parameter country_code

added the new optional query request parameter deliver_to

added the new optional query request parameter include_unshippable