Update sim/sensor_utils.py

move from msgpack to json for consistency

sim/sensor_utils.py

@@ -1,11 +1,10 @@
 """Standalone sensor utilities for camera image publishing via ZMQ"""
 import base64
+import json
 from dataclasses import dataclass
 from typing import Any, Dict
 
 import cv2
-import msgpack
-import msgpack_numpy as m
 import numpy as np
 import zmq
 
@@ -66,8 +65,8 @@ class SensorServer:
 
     def send_message(self, data: Dict[str, Any]):
         try:
-            packed = msgpack.packb(data, use_bin_type=True)
-            self.socket.send(packed, flags=zmq.NOBLOCK)
+            json_str = json.dumps(data)
+            self.socket.send_string(json_str, flags=zmq.NOBLOCK)
         except zmq.Again:
             self.message_dropped += 1
             print(f"[Warning] message dropped: {self.message_dropped}")
@@ -95,8 +94,8 @@ class SensorClient:
         self.context.term()
 
     def receive_message(self):
-        packed = self.socket.recv()
-        return msgpack.unpackb(packed, object_hook=m.decode)
+        json_str = self.socket.recv_string()
+        return json.loads(json_str)
 
 
 class ImageUtils: