[Style] Incorporate wemake-python-styleguide #253

❓ I'm submitting a ...

• 🐞 bug report
• 🐣 feature request
• ❓ question about the decisions made in the repository

🐞 Is your feature request related to a problem? Please describe.

The code style is not consistent across the project.

🐣 Describe the solution you'd like

Integrate a set of very linters to keep the style in a good shape of .

First, we need to create a legacy style baseline as per https://wemake-python-stylegui.de/en/latest/pages/usage/integrations/legacy.html and then gradually eliminate linter offenses.

This would be a great first issue for beginners.

We may need to adjust a few rules along the way, though.

📋 Describe alternatives you've considered

N/A

📋 Additional context

See also: https://wemake-python-stylegui.de/en/latest/pages/usage/integrations/flakehell.html#flakehell