Google Nest Hub on LAN crashes discovery

[hypoid]

Apparently Google Nest Hub spits out data that clobbers networkzero's discovery beacon thread every 30 seconds or so. I've narrowed it down to discovery.py's listen_for_one_advert() function.

Using a try/except clause to catch UnicodeDecodeError's appears to fix it but I'm not sure if this is "the right way to do it (TM)".