removal of vestigial gensim import

[mgudorf]

deepwalk.skipgram imports but does not use an object from gensim, Vocab , which has been removed in gensim>=4.0.0. It wasn't being used anyway so this doesn't affect anything; other than allowing deepwalk to be ran in command line once more. Technically, I only ran deepwalk --help because I just recently cloned the repo, so there could be other gensim compatibility issues elsewhere as well.

[GTmac]

Thanks for working on this! Running deepwalk --help doesn't trigger the training of DeepWalk model. Could you run DeepWalk on some graph (you could refer to the commands in README), and ensure it still works? Thank you!

[mgudorf]

Word2Vec also had a keyword argument change, namely, size was changed to vector_size; the most recent commit accounts for this; I ran the command line with default arguments in the edgelist format; unsure if there are differences in dependencies for different formats. If there's anything else you would like me to check out let me know! @GTmac

$ deepwalk --format edgelist --input edgelist.txt --output deepdish.txt
Number of nodes: 115
Number of walks: 1150
Data size (walks*length): 46000
Walking...
Training...

[mgudorf]

This is linked to issues #125 and #123 (the latter being closed)