Blinka install crashing parsing system command

[caternuson]

Re this thread:
https://forums.adafruit.com/viewtopic.php?f=60&t=174485

Looks like it got some unexpected return from running the system command:

File "/usr/local/lib/python3.7/dist-packages/adafruit_shell.py", line 75, in run_command
decoded_output = output.decode("utf-8").strip()
UnicodeDecodeError: 'utf-8' codec can't decode byte 0xa0 in position 7: invalid start byte

(full stack trace in thread)

[makermelissa]

I was unable to reproduce the issue, but I added error suppression to the offending function, which should help.