changed concat of strings to f-strings and redundant type conversion …

…was removed (#1767)

Co-authored-by: Linlang <Lv.Linlang@hotmail.com>

qlib/data/client.py

@@ -35,7 +35,7 @@ def __init__(self, host, port):
     def connect_server(self):
         """Connect to server."""
         try:
-            self.sio.connect("ws://" + self.server_host + ":" + str(self.server_port))
+            self.sio.connect(f"ws://{self.server_host}:{self.server_port}")
         except socketio.exceptions.ConnectionError:
             self.logger.error("Cannot connect to server - check your network or server status")