Make this repository work with more recent versions of python

[GiovanniPioDelvecchio]

I am just a Master's degree student, but I was searching for a library to cluster html pages and this was the first
result that I encountered.

I managed to use your commands after downloading your repository and installing it with 'pip install .'
However I had a strange error: 'no module named "html_cluster"', apparently the folder html_cluster
is not recognized as a module, so I modified the files with sys.path.append(html_cluster_path) to make
everything work again in the 'html_cluster' file of the bin folder of my conda environment and in the files of the commands
(download_html.py)

I really is a minor thing, thus I think that it should be possible for you to give it a try, maybe you can fix it quickly and re-release this package for more recent versions of python. I am using python 3.7 on a remote server running linux,
but from one of the labels on the repository I can see that you used python 3.6 to make this