ERROR: Error installing narou:
The last version of ffi (< 2, >= 0.5.0) to support your Ruby & RubyGems was 1.9.18. Try installing it with `gem install ffi -v 1.9.18` and then running the current command again
ffi requires Ruby version < 2.5, >= 2.0. The current ruby version is 2.5.0.
