[#512] chore: add type checking & lint workflow to github actions

[MSzalowski]

List of changes

• add type checking & linting to github actions

Note

That workflow won't work without #511
Also, that workflow will fail until lint errors and type errors are fixed.

Checklist

• related issue
• My changes generate no new warnings
• My code follows the style guidelines of this project
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the changelog
• I have added tests that prove my fix is effective or that my feature works

[adgud]

Why a separate workflow instead of including this in the testing one that you've just created?

[MSzalowski]

Why a separate workflow instead of including this in the testing one that you've just created?

You are right, separation makes no sense as we want to have all the checks to be passed.

[placek]

Why a separate workflow instead of including this in the testing one that you've just created?

Double that: it can be a parallel job to be done in the same workflow.

[placek]

Good job! 👍