using six.next instead of .next()

Author: Zac Pustejovsky

config/kube_config_test.py

@@ -22,7 +22,7 @@
 
 import mock
 import yaml
-from six import PY3
+from six import PY3, next
 
 from .config_exception import ConfigException
 from .kube_config import (ConfigNode, FileOrData, KubeConfigLoader,
@@ -48,7 +48,7 @@ def _format_expiry_datetime(dt):
 def _get_expiry(loader):
     expired_gcp_conf = (item for item in loader._config.value.get("users") if item.get("name") ==
                         "expired_gcp")
-    return  expired_gcp_conf.next().get("user").get("auth-provider").get("config").get("expiry")
+    return next(expired_gcp_conf).get("user").get("auth-provider").get("config").get("expiry")
 
 def _raise_exception(st):
     raise Exception(st)