Fails to build with Python 3.6

[bennahugo]

Hmm think we have a regression - forgot to raise at the time that the change made recently breaks Python 3.6 (Ubuntu 18.04 default - and the provided Dockerfile that bases off this) support - specifically this: 0074a6b

Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/optsoft/ALBUS/share/python/MS_Iono_functions.py", line 56, in <module>
    import GPS_stations
  File "/optsoft/ALBUS/share/python/GPS_stations.py", line 520, in <module>
    GPS_stations = fill_standard_stations()
  File "/optsoft/ALBUS/share/python/GPS_stations.py", line 479, in fill_standard_stations
    GPS_dict = fill_GPS_station_dict(GPS_dict, sys_file)
  File "/optsoft/ALBUS/share/python/GPS_stations.py", line 246, in fill_GPS_station_dict
    raise e
  File "/optsoft/ALBUS/share/python/GPS_stations.py", line 221, in fill_GPS_station_dict
    for line in fp:
  File "/usr/lib/python3.6/encodings/ascii.py", line 26, in decode
    return codecs.ascii_decode(input, self.errors)[0]
UnicodeDecodeError: 'ascii' codec can't decode byte 0xc3 in position 5073: ordinal not in range(128)