fixes gemspec (spree version)
fixes gemspec (spree version)

ccschmitz/spree_flexi_variants_custom,QuintinAdam/spree_flexi_variants,baraka2000/spree_flexi_variants,ccschmitz/spree_flexi_variants_custom,renuo/spree_flexi_variants,jsqu99/spree_flexi_variants,jsqu99/spree_flexi_variants,tailic/spree_flexi_variants,QuintinAdam/spree_flexi_variants,baraka2000/spree_flexi_variants,renuo/spree_flexi_variants,baraka2000/spree_flexi_variants,tailic/spree_flexi_variants,jdeen/spree_flexi_variants,jdeen/spree_flexi_variants,renuo/spree_flexi_variants,QuintinAdam/spree_flexi_variants