new hacking requirements python2 incompatible

[Tom Barron]

The new test-requirement hacking<0.13,>=0.12.0 in manila-tempest-plugin works great on master, but breaks python 2 jobs on stable branches since it requires python3. Example:

2020-04-03 17:52:36.521 | Collecting hacking<3.1.0,>=3.0 (from -r /opt/stack/new/manila-tempest-plugin/test-requirements.txt (line 5))

2020-04-03 17:52:36.558 | Could not find a version that satisfies the requirement hacking<3.1.0,>=3.0 (from -r /opt/stack/new/manila-tempest-plugin/test-requirements.txt (line 5)) (from versions: 0.5.0, 0.5.1, 0.5.2, 0.5.3, 0.5.4, 0.5.5, 0.5.6, 0.6.0, 0.7.0, 0.7.1, 0.7.2, 0.8.0, 0.8.1, 0.9.0, 0.9.1, 0.9.2, 0.9.3, 0.9.4, 0.9.5, 0.9.6, 0.9.7, 0.10.0, 0.10.1, 0.10.2, 0.10.3, 0.11.0, 0.12.0, 0.13.0, 1.0.0, 1.1.0, 2.0.0)

2020-04-03 17:52:36.561 | No matching distribution found for hacking<3.1.0,>=3.0 (from -r /opt/stack/new/manila-tempest-plugin/test-requirements.txt (line 5))

devstack setup fails

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.opendev.org/717395

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.opendev.org/717395
Committed: https://git.openstack.org/cgit/openstack/manila-tempest-plugin/commit/?id=ad6f7de944c78168f7cb567e6999ea40068fafeb
Submitter: Zuul
Branch: master

commit ad6f7de944c78168f7cb567e6999ea40068fafeb
Author: Tom Barron <email address hidden>
Date: Fri Apr 3 17:04:12 2020 -0400

    Fix hacking test requirement

    A recent change [1] updated the hacking version
    in manila-tempest-plugin and made corresponding
    fixes but unfortunately is python 2 incompatible.
    We really only need hacking on master anyways,
    where we no longer support python 2, so here we
    make the requirement specific to python 3.

    [1] https://review.opendev.org/#/c/716559

    Closes-bug: #1870621

    Change-Id: I9771cf31d50dbbfc0eb978ffb8f485c431cf2767