Code quality improvements - adress findings from www.codefactor.io

[napetrov]

Please create PRs for addressing code quality issues reported by codefactor scans

https://www.codefactor.io/repository/github/IntelPython/scikit-learn_bench

Some problems are simple fixes and i would expect that they can be fixed across entire repo and not one by one
Other might be super complex and i don't think can be fixed without serious refactoring - code complexity

[LyndonFan]

Hi, is this issue available? I can try to work on it!

[napetrov]

@LyndonFan - yes, sure. Please open PRs with fixes