Requirements upper constraints bumped python-novaclient to version
18.0.0 [1], which requires Python 3.8 [2]. This results in failures when
installing python-openstackclient on CentOS and Rocky with Python 3.6.

    ERROR: Cannot install python-openstackclient==5.8.0 because these package versions have conflicting dependencies.

    The conflict is caused by:
        python-openstackclient 5.8.0 depends on python-novaclient>=17.0.0
        The user requested (constraint) python-novaclient===18.0.0

Work around this issue by using yoga upper constraints until we upgrade
to CentOS Stream 9 and Rocky Linux 9.

This also fixes another issue seen on Ubuntu where image uploads to
Glance through Ansible fail with a 400 Bad Request error. This is caused
by the bump of openstacksdk to version 0.99.0 and will be fixed by a new
release of ansible-collections-openstack.

[1] https://review.opendev.org/c/openstack/requirements/+/842808
[2] https://review.opendev.org/c/openstack/python-novaclient/+/838944

Change-Id: I40c6b898963c2218d41d37bd73d40ce8dcf22b87