Change Mistral py3 jobs non-voting to voting.
Change Mistral py3 jobs non-voting to voting.

Change-Id: Ic6830f25151b4f04220b0357ef606df81180db19
Partially-Implements: blueprint mistral-py3

dongwenjuan/project-config,noorul/os-project-config,Tesora/tesora-project-config,Tesora/tesora-project-config,noorul/os-project-config,openstack-infra/project-config,openstack-infra/project-config,dongwenjuan/project-config