log exception as warning

[fbaptista]

Don’t thrown an error when InstrumentsServer shows this warning:

(16132 InstrumentServer) [ERROR] unpack requires a buffer of 64 bytes
   96  Traceback (most recent call last):
   97    File "C:\hostedtoolcache\windows\Python\3.9.6\x64\lib\site-packages\py_ios_device-2.1.1-py3.9.egg\ios_device\util\utils.py", line 114, in kperf_data
   98: struct.error: unpack requires a buffer of 64 bytes