fix: 修复由于mqtt上报时间大于服务器时间导致计算bug问题

apps/counter/api/serializers.py

@@ -238,8 +238,8 @@ class DeviceInfoSerializer(serializers.ModelSerializer):
             mosq_device_info = MosquitoDeviceInfo.objects.filter(device_id=obj.device_id).first()
             if mosq_device_info and mosq_device_info.last_connect:
                 self.mosq_device_info = mosq_device_info
-                now = datetime.now(tz=pytz.timezone('Asia/Shanghai'))
-                dt = now - mosq_device_info.last_connect
+                now = datetime.now(pytz.utc)
+                dt = abs(now - mosq_device_info.last_connect)
                 if dt.seconds > 300:
                     return 0
                 else: