[Suggestion] Ignore errors on encoding a known message

[snirsh]

Hi, I've been testing this for some time now and I see some errors regarding a 'feed' with the error I've mentioned before:

feeder.util.mqtt.client: Failed to decode message: bytearray(b'{"_|deviceHid":"89dfa32aa126ff9964811ffffdf7e1c69c43b82a","s|msg_type":"trace","i|tl":32,"s|ts":"Start - D\xdf, Portion: 0 tbsp(309448g), Turns: 26, Bowl: 0g, Hopp"}')

This is due to ".../mqtt/client.py", line 102, handle_message, would suggest json.loads(packet.payload.data, 'ignore') which will ignore this small problem.

[snirsh]

small fix:

this should probably be:

decoded_payload = packet.payload.data.decode('utf-8', 'ignore')
payload = json.loads(decoded_payload)