Remove reference to FactoryGirl

spec/models/spree/return_authorization_spec.rb

@@ -3,7 +3,7 @@
 require 'spec_helper'
 
 describe Spree::ReturnAuthorization do
-  let(:order) { FactoryGirl.create(:shipped_order) }
+  let(:order) { create(:shipped_order) }
   let(:variant) { order.shipments.first.inventory_units.first.variant }
   let(:return_authorization) { Spree::ReturnAuthorization.new(order: order) }