Fix bthome UnitOfConductivity (#129535)

Fix unit

homeassistant/components/bthome/sensor.py

@@ -364,7 +364,7 @@ SENSOR_DESCRIPTIONS = {
     ): SensorEntityDescription(
         key=f"{BTHomeSensorDeviceClass.CONDUCTIVITY}_{Units.CONDUCTIVITY}",
         device_class=SensorDeviceClass.CONDUCTIVITY,
-        native_unit_of_measurement=UnitOfConductivity.MICROSIEMENS,
+        native_unit_of_measurement=UnitOfConductivity.MICROSIEMENS_PER_CM,
         state_class=SensorStateClass.MEASUREMENT,
     ),
 }