Autofix Rubocop Style/StringLiterals (#23695)

spec/fabricators/user_fabricator.rb

@@ -1,7 +1,7 @@
 Fabricator(:user) do
   account      { Fabricate.build(:account, user: nil) }
   email        { sequence(:email) { |i| "#{i}#{Faker::Internet.email}" } }
-  password     "123456789"
+  password     '123456789'
   confirmed_at { Time.zone.now }
   agreement    true
 end