Identical values for many hours for Temp&Humid when connection to device is lost
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Hello,

I'm using homebridge-mi-hygrothermograph 3.0.1 and sometimes see that in EVE history Temp&Humid values are the same for many hours. I've also checked in JSON - the same values for many hours. Looks like plugin auto repeats previous values to history when no new readings.

### Expected Behavior
Temp and Humid values shouldn't be repeated if there is no new values.

### Current Behavior
Temp and Humid values are repeated if there is no connection to Device.

### Steps to Reproduce (for bugs)
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### Versions
<!-- Please run commands and include versions below. -->
- **homebridge**: v1.1.6 
- **homebridge-mi-hygrothermograph**: 3.0.1
- **node**:       v12.19.0
- **OS**:        Raspbian Buster


### Configuration

```json
{
            "name": "Temperature & Humidity",
            "address": "xxxxxxxxx",
            "temperatureName": "Temperature",
            "humidityName": "Humidity",
            "fakeGatoEnabled": true,
            "timeout": 30,
            "forceDiscovering": true,
            "forceDiscoveringDelay": 120,
            "disableBatteryLevel": false,
            "lowBattery": 10,
            "temperatureOffset": 0,
            "humidityOffset": 0,
            "accessory": "Hygrotermograph"
        },
```

