easier install by specifying python version and torch using pip

[FarisHijazi]

I'm just trying to make installations easier

it seems that in this repo, they use python 3.7

and installation is completely through pip (which is much easier than having to figure things out)

pip install --no-cache-dir -r requirements.txt
pip install torch==1.8.1+cu111 torchvision==0.9.1+cu111 torchaudio===0.8.1 -f https://download.pytorch.org/whl/torch_stable.html

it would be handy if you just mentioned this in the README.md

thanks for vocal-remover