a minor key causes issue with bar.determine_progression from mingus

[Avantol13]

---

-------------------------- Music Generator Output -------------------------

Time Signature: (4, 4)
Key: a
Scale: ['A', 'B', 'C', 'D', 'E', 'F', 'G', 'A']
Progression: ['I', 'V', 'vi', 'iii']
--------------------------------- Bar 0 ----------------------------------
Melody Timing: [[8], [4], [4], [16, 16, 16, 16], [16, 16]]
Chosen Notes: ['E', 'D', 'A', None, 'A', None, 'G', 'G', 'D']
TESTING STUFF...
[[0.0, ['E']], [0.125, ['D']], [0.375, ['A']], [0.6875, ['A']], [0.8125, ['G']], [0.875, ['G']], [0.9375, ['D']]]
Traceback (most recent call last):
File "C:\Users\TheGoobster\Documents\GitHub\music_generator\main.py", line 120, in
main()
File "C:\Users\TheGoobster\Documents\GitHub\music_generator\main.py", line 102, in main
melody_track = create.create_melody_track(num_bars, config['key'], time_signature)
File "C:\Users\TheGoobster\Documents\GitHub\music_generator\music_generator\create.py", line 61, in create_melody_track
print(bar_to_add.determine_progression(shorthand=True))
File "C:\Users\TheGoobster\Documents\GitHub\music_generator\mingus\containers\bar.py", line 197, in determine_progression
self.key.key, shorthand)])
File "C:\Users\TheGoobster\Documents\GitHub\music_generator\mingus\core\progressions.py", line 151, in determine
(interval_type, interval) = intervals.determine(key, name).split(' ')
File "C:\Users\TheGoobster\Documents\GitHub\music_generator\mingus\core\intervals.py", line 356, in determine
n1 = notes.fifths.index(note1[0])
ValueError: 'a' is not in list