Fix CI: pin cucumber 3
Fix CI: pin cucumber 3

CI fails with cucumber 4:
https://travis-ci.org/artem-sidorenko/chef-cups/jobs/438859615

Signed-off-by: Artem Sidorenko <15a0730a27c69f62ab86f2b6c639fca202166c02@posteo.de>

artem-sidorenko/chef-cups,artem-sidorenko/chef-cups,biola/chef-cups,biola/chef-cups,artem-sidorenko/chef-cups