Update unicode-display_width gem to 1.4.0
Update unicode-display_width gem to 1.4.0

This elmiminates the deprecation warning in rubocop:

"NOTE: Gem.gunzip is deprecated; use Gem::Util.gunzip instead. It will
be removed on or after 2018-12-01."

gitlabhq/omnibus-gitlab,gitlabhq/omnibus-gitlab,gitlabhq/omnibus-gitlab,gitlabhq/omnibus-gitlab