Try avoiding an unknown constant error

Workaround from hotwired/turbo-rails#512 (comment)'

Author: olleolleolle

config/application.rb

@@ -11,7 +11,7 @@
 require "action_mailbox/engine"
 require "action_text/engine"
 require "action_view/railtie"
-# require "action_cable/engine"
+require "action_cable/engine"
 require "sprockets/railtie"
 require "rails/test_unit/railtie"