Apply manual rubocop fixes

spec/policies/external_user_policy_spec.rb

@@ -3,14 +3,14 @@
 require 'rails_helper'
 
 describe ExternalUserPolicy do
-  subject { described_class }
+  subject(:policy) { described_class }
 
   %i[create? destroy? edit? new? show? update?].each do |action|
     permissions(action) do
       it 'grants access to admins only' do
-        expect(subject).to permit(FactoryBot.build(:admin), ExternalUser.new)
+        expect(policy).to permit(FactoryBot.build(:admin), ExternalUser.new)
         %i[external_user teacher].each do |factory_name|
-          expect(subject).not_to permit(FactoryBot.build(factory_name), ExternalUser.new)
+          expect(policy).not_to permit(FactoryBot.build(factory_name), ExternalUser.new)
         end
       end
     end
@@ -19,10 +19,10 @@ describe ExternalUserPolicy do
   [:index?].each do |action|
     permissions(action) do
       it 'grants access to admins and teachers only' do
-        expect(subject).to permit(FactoryBot.build(:admin), ExternalUser.new)
-        expect(subject).to permit(FactoryBot.build(:teacher), ExternalUser.new)
+        expect(policy).to permit(FactoryBot.build(:admin), ExternalUser.new)
+        expect(policy).to permit(FactoryBot.build(:teacher), ExternalUser.new)
         [:external_user].each do |factory_name|
-          expect(subject).not_to permit(FactoryBot.build(factory_name), ExternalUser.new)
+          expect(policy).not_to permit(FactoryBot.build(factory_name), ExternalUser.new)
         end
       end
     end