gensim update needed

[DanilSko]

change for word in model to for word in model.wv to make the notebook compatible with the latest gensim. also model.most_similar to model.wv.most_similar

[nevmenandr]

more corrections here: https://github.com/piskvorky/gensim/wiki/Migrating-from-Gensim-3.x-to-4