Comment 3 for bug 1889380

The warning seems to be coming from tripleo_common project from line [1]

Changing it to filter only deprecation warnings fixes it
~~~
warnings.filterwarnings('once', category=DeprecationWarning)
~~~

[1] https://opendev.org/openstack/tripleo-common/src/branch/master/tripleo_common/utils/config.py#L36