Update reference to ActionCable
Update reference to ActionCable

action_cable renamed to actioncable in newer versions of Rails. Renamed
for deprecation warnings (and in prep for Rails 8).

tomnatt/year-in-pictures-rails-helper,tomnatt/year-in-pictures-rails-helper,tomnatt/year-in-pictures-rails-helper,tomnatt/year-in-pictures-rails-helper