openstack-service-checks using keystoneclient instead of keystoneauth1

Charm openstack-service-checks is using keystoneclient (which is deprecated) instead of keystoneauth1

Noticed this issue while running openstack-service-checks functional tests, we can see the following warning messages in the logs

unit-openstack-service-checks-4: 18:12:32 WARNING unit.openstack-service-checks/4.identity-notifications-relation-changed /usr/lib/python3/dist-packages/keystoneauth1/adapter.py:179: UserWarning: Using keystoneclient sessions has been deprecated. Please update your software to use keystoneauth1.
unit-openstack-service-checks-4: 18:12:32 WARNING unit.openstack-service-checks/4.identity-notifications-relation-changed warnings.warn('Using keystoneclient sessions has been deprecated. '
unit-openstack-service-checks-4: 18:12:32 INFO juju.worker.uniter.operation ran "identity-notifications-relation-changed" hook (via explicit, bespoke hook script)
unit-nagios-3: 18:12:53 INFO juju.worker.uniter.operation skipped "update-status" hook (missing)

To reproduce this issue please use the bundle.yaml attached and add any of the following relations

juju add-relation keystone:identity-credentials openstack-service-checks:identity-credentials
juju add-relation keystone:identity-notifications openstack-service-checks:identity-notifications

And use "juju debug-log" to watch log output and the above warning messages

juju-crashdump file is attached

The following application versions were used

cs:keystone-323
cs:nagios-44
cs:nrpe-73
cs:~canonical-bootstack/openstack-service-checks-32
cs:percona-cluster-29