HS103: Unable to query the device: unpack requires a buffer of 4 bytes

With an HS103 on a local network. Tested with Raspbian/Py3.7 and Windows/Py3.8. Both come back with:


```
Traceback (most recent call last):
  File "/home/pi/.local/lib/python3.7/site-packages/kasa/protocol.py", line 64, in query
    length = struct.unpack(">I", chunk[0:4])[0]
struct.error: unpack requires a buffer of 4 bytes

```

Worth noting that the hs103 can be discovered. 