Update to the terms of contribution

[o-murphy]

Prerelease v2.0.4rc1 was published, in which type annotations were updated according to mypy standard requirements.

First thing you have to know - v2.0.4-v2.0.xx will save full API backward compatibility with previous versions starting from v2.0.0.

Most type annotations have already been fixed, except for unit, backend modules and optional support for pandas and matplotlib.

Removed redundant types and functions. Updated initialization of dataclasses.

Since future version v2.0.4 all the merge requests waiting for a merge will require types annotation check passing through mypy.

Also since v2.0.4 it require pylint analysing with pass with result >9.5

Before the final v2.0.4 deployment, github workflows scenaries would be adjusted for new contribution specs