Remove dead code: Shipment#total_cost

app/models/spree/shipment.rb

@@ -164,10 +164,6 @@ module Spree
       Spree::Money.new(item_cost, currency: currency)
     end
 
-    def total_cost
-      cost + item_cost
-    end
-
     def editable_by?(_user)
       !shipped?
     end

spec/models/spree/shipment_spec.rb

@@ -174,12 +174,6 @@ describe Spree::Shipment do
     end
   end
 
-  it '#total_cost' do
-    allow(shipment).to receive_messages cost: 5.0
-    allow(shipment).to receive_messages item_cost: 50.0
-    expect(shipment.total_cost).to eql(55.0)
-  end
-
   context "#update!" do
     shared_examples_for "immutable once shipped" do
       it "should remain in shipped state once shipped" do