Change ThreadPoolExecutor to ProcessPoolExecutor?

[oalieno]

asm2vec/asm2vec/internal/repr.py

Line 105 in 6e975f0

executor = concurrent.futures.ThreadPoolExecutor(max_workers=jobs)

asm2vec/asm2vec/internal/training.py

Line 286 in 6e975f0

executor = concurrent.futures.ThreadPoolExecutor(max_workers=context.params().jobs)

Using thread to handle CPU-bound tasks in python may not be helpful due to the issue of GIL.