Server listener and client connections have is_server set. (#2338)

pymodbus/server/async_io.py

@@ -43,7 +43,7 @@ def __init__(self, owner):
             host=owner.comm_params.source_address[0],
             port=owner.comm_params.source_address[1],
         )
-        super().__init__(params, False)
+        super().__init__(params, True)
         self.server = owner
         self.running = False
         self.receive_queue: asyncio.Queue = asyncio.Queue()