feat(core): make DNS resolution error retriable (#631)

DNS resolution errors were previously not retriable, this commit allows it by changing the value returned when the DNS resolution fails.

Author: ksarabu1

kazoo/protocol/connection.py

@@ -543,7 +543,7 @@ def _connect_loop(self, retry):
 
         # Check for an empty hostlist, indicating none resolved
         if len(host_ports) == 0:
-            return STOP_CONNECTING
+            raise ForceRetryError('No host resolved. Reconnecting')
 
         for host, hostip, port in host_ports:
             if self.client._stopped.is_set():