Change args passed to Word2Vec class

[pedroruas18]

The args "size" and "iter" (line 87, in the script "src/main.py") are no longer used in Gensim.4.0 (see https://github.com/RaRe-Technologies/gensim/wiki/Migrating-from-Gensim-3.x-to-4), which throws an error, so I changed them to "vector_size" and "epochs", respectively.