[WIP] Fix authenticity token failure in Rails example

[hummusonrails]

This pull request adds the following setting in the configuration of the example Rails application:

config.action_controller.default_protect_from_forgery = true

Before doing so, the application would not start and instead exited with the following error:

ArgumentError (Before process_action callback :verify_authenticity_token has not been defined):

The Rails 7 example Gemfile is also updated to reflect the current release on the Rails v7 line.