Expand array for GLONASS and GALILEO

[mict-ss]

Suggestion for file Adafruit_GPS.h

line 251/252:
const char *sources[6] = {"II", "WI", "GP", "GN", "P", "ZZZ"};

Change to:
const char *sources[8] = {"II", "WI", "GP", "GL", "GA", "GN", "P", "ZZZ"};

GP = GPS
GL = GLONASS (to be added)
GA = GALILEO (to be added)

[targetarchitecture]

@mict-ss have you tested this?

[svdrummer]

Is this still active?