Remove explicit distribute depend.
Remove explicit distribute depend.

Causes issues with the recent re-merge with setuptools. Advice from
upstream is to stop doing explicit depends.

Change-Id: I04fb8c9ebc7c8dbab7fb027865da2ffbfaa3c229

faizan-barmawer/ironic-lib,openstack/ironic-lib,citrix-openstack-build/ironic-lib,NaohiroTamura/ironic-lib,faizan-barmawer/elytics