Remove freeze method call at csv_header

app/models/account.rb

@@ -18,6 +18,6 @@ class Account < ApplicationRecord
   end
 
   def self.csv_header
-    ['Id', 'Balance', 'Currency', 'Registrar'].freeze
+    ['Id', 'Balance', 'Currency', 'Registrar']
   end
 end

app/models/contact.rb

@@ -590,6 +590,6 @@ class Contact < ApplicationRecord
   end
 
   def self.csv_header
-    ['Name', 'ID', 'Ident', 'E-mail', 'Created at', 'Registrar', 'Phone'].freeze
+    ['Name', 'ID', 'Ident', 'E-mail', 'Created at', 'Registrar', 'Phone']
   end
 end

app/models/domain.rb

@@ -779,7 +779,7 @@ class Domain < ApplicationRecord
   end
 
   def self.csv_header
-    ['Domain', 'Registrant', 'Valid to', 'Registrar', 'Created at', 'Statuses', 'Contacts code', 'Force delete date', 'Force delete data'].freeze
+    ['Domain', 'Registrant', 'Valid to', 'Registrar', 'Created at', 'Statuses', 'Contacts code', 'Force delete date', 'Force delete data']
   end
 
   def self.pdf(html)

app/models/invoice.rb

@@ -131,7 +131,7 @@ class Invoice < ApplicationRecord
   end
 
   def self.csv_header
-    ['Number', 'Buyer', 'Due Date', 'Receipt Date', 'Issue Date', 'Total', 'Currency', 'Seller Name'].freeze
+    ['Number', 'Buyer', 'Due Date', 'Receipt Date', 'Issue Date', 'Total', 'Currency', 'Seller Name']
   end
 
   def self.create_from_transaction!(transaction)

app/models/version/contact_version.rb

@@ -19,6 +19,6 @@ class Version::ContactVersion < PaperTrail::Version
   end
 
   def self.csv_header
-    ['Name', 'ID', 'Ident', 'Registrar', 'Action', 'Created at'].freeze
+    ['Name', 'ID', 'Ident', 'Registrar', 'Action', 'Created at']
   end
 end

app/models/version/domain_version.rb

@@ -57,6 +57,6 @@ class Version::DomainVersion < PaperTrail::Version
   end
 
   def self.csv_header
-    ['Name', 'Registrant', 'Registrar', 'Action', 'Created at'].freeze
+    ['Name', 'Registrant', 'Registrar', 'Action', 'Created at']
   end
 end