Cleanup test

The `subscription` and `invitiation` variables weren't used, so I've got rid of them

Author: jonodrew

spec/features/member_portal_spec.rb

@@ -20,8 +20,8 @@
 
       it 'can view attending workshops' do
         workshop = Fabricate(:workshop, chapter: Fabricate(:chapter_with_groups))
-        subscription = Fabricate(:subscription, member: member, group: workshop.chapter.groups.first)
-        invitation = Fabricate(:attending_workshop_invitation, member: member,
+        Fabricate(:subscription, member: member, group: workshop.chapter.groups.first)
+        Fabricate(:attending_workshop_invitation, member: member,
                                                                workshop: workshop)
         presenter = WorkshopPresenter.new(workshop)
         visit dashboard_path