Use upper constraints for all jobs in tox.ini
Use upper constraints for all jobs in tox.ini

Openstack infra now supports upper constraints for
all jobs. Updated tox.ini to use upper constraints
for all jobs.

Change-Id: Ib0a64dfee279b1a68c415bcbaf395b3bf040c7ff
Closes-Bug: #1614361

openstack/designate,openstack/designate,openstack/designate