Add :turbo_stream as a default navigational format

[nickrivadeneira]

Fixes #5439

Rails 7 returns :turbo_stream as a request format out-of-the-box. I'm on the fence whether this is the right change to make or if it should be left up to the user to add it as a configuration in their initializer. I opted to open the PR since it is a format that a vanilla Rails 7 app will use, which means vanilla Devise will break with vanilla Rails without this change.

Feel free to close if it's best left as-is.