Add frozen_string_literal magic comment

re: https://www.rubydoc.info/gems/rubocop/RuboCop/Cop/Style/FrozenStringLiteralComment

.rubocop.yml

@@ -17,8 +17,6 @@ AllCops:
 #################### Metrics ###############################
 
 # Start with cops for Ruby >= 2.3 disabled
-Style/FrozenStringLiteralComment:
-  Enabled: false
 Style/SafeNavigation:
   Enabled: false
 Style/NumericPredicate:

app/views/admin/booths/_all_booths.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb.add_worksheet(name: 'all booths') do |sheet|
   bold_style = wb.styles.add_style(b: true)
   wrap_text = wb.styles.add_style alignment: {wrap_text: true}

app/views/admin/booths/_confirmed_booths.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb.add_worksheet(name: 'all booths') do |sheet|
   bold_style = wb.styles.add_style(b: true)
   wrap_text = wb.styles.add_style alignment: {wrap_text: true}

app/views/admin/booths/booths.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb = xlsx_package.workbook
 xlsx_package.use_autowidth = true
 if @booth_export_option == 'confirmed'

app/views/admin/events/_all_events.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb.add_worksheet(name: 'all events') do |sheet|
   bold_style = wb.styles.add_style(b: true)
   wrap_text = wb.styles.add_style alignment: {wrap_text: true}

app/views/admin/events/_all_with_comments.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb.use_shared_strings = true
 wb.add_worksheet(name: 'events with comments') do |sheet|
   bold_style = wb.styles.add_style(b: true)

app/views/admin/events/_confirmed_events.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb.add_worksheet(name: 'confirmed events') do |sheet|
   bold_style = wb.styles.add_style(b: true)
   wrap_text = wb.styles.add_style alignment: {wrap_text: true}

app/views/admin/events/events.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb = xlsx_package.workbook
 if @event_export_option == 'confirmed'
   render partial: 'confirmed_events', locals: {:wb => wb}

app/views/admin/registrations/index.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb = xlsx_package.workbook
 wb.add_worksheet(name: 'registrations') do |sheet|
   bold_style = wb.styles.add_style(b: true)

app/views/admin/tracks/_all_tracks.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb.add_worksheet(name: 'all tracks') do |sheet|
   bold_style = wb.styles.add_style(b: true)
   wrap_text = wb.styles.add_style alignment: {wrap_text: true}

app/views/admin/tracks/_confirmed_tracks.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb.add_worksheet(name: 'all tracks') do |sheet|
   bold_style = wb.styles.add_style(b: true)
   wrap_text = wb.styles.add_style alignment: {wrap_text: true}

app/views/admin/tracks/tracks.xlsx.axlsx

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 wb = xlsx_package.workbook
 if @track_export_option == 'confirmed'
   render partial: 'confirmed_tracks', locals: { wb: wb }

db/migrate/20180316185150_add_code_of_conduct_to_organization.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AddCodeOfConductToOrganization < ActiveRecord::Migration[5.0]
   def change
     add_column :organizations, :code_of_conduct, :text

db/migrate/20180316220446_add_accepted_code_of_conduct_to_registrations.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 class AddAcceptedCodeOfConductToRegistrations < ActiveRecord::Migration[5.0]
   def change
     add_column :registrations, :accepted_code_of_conduct, :boolean

spec/features/code_of_conduct_spec.rb

@@ -1,3 +1,5 @@
+# frozen_string_literal: true
+
 require 'spec_helper'
 
 feature 'Code of Conduct:' do