PyCodeStyle

[nettle]

Describe the task

Introduce pycodestyle for python code verification

Scope

1. Find an elegant and reliable way to add pycodestyle to the project
2. Define very simple, first iteration of pycodestyle workflow and rules
3. Suggest simple, easy-to-use pycodestyle configuration
4. Plan cleanup and CI integration as next steps

Definition of Done

• Clear for all developers how to use pycodestyle in the project
• Simple requirements are described
• CONTRIBUTING is updated