Fix default protocol parser version

Author: dpkp

kafka/conn.py

@@ -230,6 +230,9 @@ def __init__(self, host, port, afi, **configs):
 
         self.node_id = self.config.pop('node_id')
 
+        if self.config['api_version'] is None:
+            self.config['api_version'] = self.DEFAULT_CONFIG['api_version']
+
         if self.config['receive_buffer_bytes'] is not None:
             self.config['socket_options'].append(
                 (socket.SOL_SOCKET, socket.SO_RCVBUF,