make tag_hotspots compatible with python3

[ionox0]

changes need to be made to:

line 61, 73, 74

with open(args.input_txt, 'rb') as infile:
to
with open(args.input_txt, 'r') as infile:

with open(args.input_maf, 'rb') as infile:
to
with open(args.input_maf, 'r') as infile:

with open(args.output_maf, 'wb') as outfile:
to
with open(args.output_maf, 'w') as outfile:

and confirm that this still works in python2.7

similarly, all scripts should be ported to python3 ideally