Remove last occurrence of BarAbility

It's deprecated but the deprecation message was silenced for some
reason. This commit allow us to avoid using that class switching
to an anonymous class that does the same.

core/spec/models/spree/ability_spec.rb

@@ -98,7 +98,17 @@ def initialize(_user)
       it 'should be able to admin on the order and shipment pages' do
         user.spree_roles << Spree::Role.find_or_create_by(name: 'bar')
 
-        Spree::Ability.register_ability(BarAbility)
+        bar_ability = Class.new do
+          include CanCan::Ability
+
+          def initialize(user)
+            if user.has_spree_role? 'bar'
+              can [:admin, :index, :show], Spree::Order
+              can [:admin, :manage], Spree::Shipment
+            end
+          end
+        end
+        Spree::Ability.register_ability(bar_ability)
 
         expect(ability).not_to be_able_to :admin, resource