Update the bundle (only affects specs).
Replace deprecated #stub! rspec calls with #stub.
Cache the `file` output in #detect_type_by_contents.

This means we can spec that it's called exactly once, removing the
deprecated #any_number_of_times call. Performs better, too.
Remove #any_number_of_times calls in the Prompt specs.

In both cases, #tty? will always be called twice; #any_number_of_times
wasn't strict enough.