Testinfra works with Ansible 2.8.0 now, so we can update
bridge.opendev.org to the latest version. This also needs an ARA
update; bring it to the latest 0.16.4 release.
Update test-requirements so that tox/ansible-lint use Ansible 2.8.0
too. See note inline about dependencies.
Note we replace import_tasks with include_tasks in handlers to address
this porting issue:
https://docs.ansible.com/ansible/latest/porting_guides/porting_guide_2.8.html#imports-as-handlers
Change-Id: I7ed75d253857f86b68f67023af6897af4e1b4f50
8a06d48c84