Fix positional params used for `gensim.models.CoherenceModel` in `gensim.models.callbacks` (#1823)
Fix positional params used for `gensim.models.CoherenceModel` in `gensim.models.callbacks` (#1823)

* add keyword params for call to gensim.models.CoherenceModel as positional arguments for coherence and topn were incorrect due to skipping param for keyed_vectors

* Fix PEP8

mattilyra/gensim,gojomo/gensim,RaRe-Technologies/gensim,mattilyra/gensim,RaRe-Technologies/gensim,mattilyra/gensim,gojomo/gensim,gojomo/gensim,piskvorky/gensim,RaRe-Technologies/gensim,piskvorky/gensim,RaRe-Technologies/gensim,piskvorky/gensim,gojomo/gensim