Fix the exceptions import

Change-Id: I804daa0e2b3c8f7a9d421449afcf1e057b8c63c8

contrib/plugins/magnum_plugin/magnum_plugin/__init__.py

@@ -20,11 +20,7 @@ from murano.common import auth_utils
 from murano.dsl import session_local_storage
 from oslo_config import cfg as config
 
-try:
-    from magnumclient.common.apiclient import exceptions
-except ImportError:
-    # NOTE (hongbin): For magnumclient versions before 2.0.0.
-    from magnumclient.openstack.common.apiclient import exceptions
+from magnumclient import exceptions
 
 CONF = config.CONF