Remove testify dependency as not used any more
Remove testify dependency as not used any more

Signed-off-by: Justin Cormack <af64ee19f04db9509cb02b0e470e11e5402ef9b3@docker.com>

cpuguy83/cli,thaJeztah/cli,thaJeztah/cli,docker/cli,docker/cli,cpuguy83/cli