remove duplicate let in update service shared example

spec/services/base_services/behaves_like_update_service.rb

@@ -34,7 +34,6 @@ RSpec.shared_examples "BaseServices update service" do
   let(:service_class) { described_class }
   let(:namespace) { service_class.to_s.deconstantize }
   let(:model_class) { namespace.singularize.constantize }
-  let(:contract_class) { "#{namespace}::UpdateContract".constantize }
   let(:factory) { namespace.singularize.underscore }
 
   let(:set_attributes_class) { "#{namespace}::SetAttributesService".constantize }