Use Bionic for translation jobs
Use Bionic for translation jobs

We need Python 3.6 for master, update to Bionic. The update
should be ok since we install openjdk 8 on Bionic now.

Depends-On: https://review.opendev.org/702515
Change-Id: I858a34c09c501b0e2e8b2d70e6ff75fe32495571

openstack-infra/project-config,openstack-infra/project-config