The app scanner for ActionCable should check if the config needs Redis

[albus522]

Right now, if ActionCable is being using, we try to add redis even if ActionCable is not configured to use redis. It would be better to make the check a bit smarter in determining if redis is actually required.

[rubys]

Take a peek at https://github.com/fly-apps/dockerfile-rails/blob/main/lib/dockerfile-rails/scanner.rb, and look for references to anycable.

Also, you can experiment with:

bin/rails console
> YAML.load_file('config/cable.yml')