Fix Rails 6.0 build
Fix Rails 6.0 build

zambot/rails_admin,dalpo/rails_admin,widgetworks/rails_admin,sferik/rails_admin,sferik/rails_admin,widgetworks/rails_admin,zambot/rails_admin,dalpo/rails_admin,dalpo/rails_admin,zambot/rails_admin,sferik/rails_admin,widgetworks/rails_admin