Autofix Rubocop RSpec/LeadingSubject (#23670)

spec/lib/activitypub/activity/undo_spec.rb

@@ -1,6 +1,8 @@
 require 'rails_helper'
 
 RSpec.describe ActivityPub::Activity::Undo do
+  subject { described_class.new(json, sender) }
+
   let(:sender) { Fabricate(:account, domain: 'example.com') }
 
   let(:json) do
@@ -13,8 +15,6 @@ RSpec.describe ActivityPub::Activity::Undo do
     }.with_indifferent_access
   end
 
-  subject { described_class.new(json, sender) }
-
   describe '#perform' do
     context 'with Announce' do
       let(:status) { Fabricate(:status) }