Remove pinned versions from test-requirements.txt
Remove pinned versions from test-requirements.txt

As we are using the upper constraints when running the release
notes task using tox, we do not need to set a specific version
and we can rely on whatever is configured in upper constraints.

Change-Id: I9245cf05e5d1df4d9ddd1c38e15c318858b9fd2d
Co-Authored-By: Mohammed Naser <a3a66f39ffe9826175451451c8354a04dc2bf5ca@vexxhost.com>

openstack/puppet-trove,openstack/puppet-trove,openstack/puppet-trove