Drop python 2.7 support and testing

Change-Id: I3ff7a714d5fd61edd72e00c7a454c81724844f99
Closes-bug: #1853372
diff --git a/.zuul.yaml b/.zuul.yaml
index 3a9ff16..cfb739d 100644
--- a/.zuul.yaml
+++ b/.zuul.yaml
@@ -28,6 +28,7 @@
       devstack_localrc:
         CINDER_ISCSI_HELPER: lioadm
         TEMPEST_PLUGINS: /opt/stack/cinder-tempest-plugin
+        USE_PYTHON3: true
       devstack_plugins:
         barbican: https://opendev.org/openstack/barbican
       devstack_services: