Shelly Dimmer 1 not discovered by plugin, but "shellies listen" working
**Describe the bug**
Shelly Dimmer 1 not discovered by plugin, but no network issues as "shellies listen" works just fine.

**Log output**
```
16.11.2020, 18:03:12 [Shelly] Initializing Shelly platform...
16.11.2020, 18:03:12 [Shelly] 0 accessories loaded from cache
16.11.2020, 18:03:13 Bridge is running on port 51826.
16.11.2020, 18:03:13 [Shelly] Admin server is running on port 8181
```
**Environment:**
 - Shelly device(s): Shelly Dimmer 1
 - Plugin version: 0.15.7
 - Device running homebridge: Pi zero v1.3 
 - HOOBS 3.2.10
 - Node 12.19.0

Shellies listen works:
```
hoobs@hoobs:/home/hoobs/.hoobs/etc $ shellies listen
[Device discovered] 2020-11-16T17:09:38.532Z
Model: Shelly Dimmer ID: D0A8BC Host: 10.0.1.51
Property: switch Value: false
Property: brightness Value: 100
Property: input0 Value: 0
Property: inputEvent0 Value: L
Property: inputEventCounter0 Value: 35
Property: input1 Value: 0
Property: inputEvent1 Value: 
Property: inputEventCounter1 Value: 0
Property: power0 Value: 0
Property: energyCounter0 Value: 4904
Property: overPower Value: false
Property: loadError Value: false
Property: deviceTemperature Value: 43.08
Property: overTemperature Value: false
Property: mode Value: white
```

plugin admin site:
```
homebridge-shelly
No devices discovered
```