This change removes the dependency on platform provided protobuf tools
in favour of `grpcio-tools` dependency. This makes both development and
compiler use independent from platform dependencies.
- dropped dev dependency on rope, isort & flake
- poetry doesn't support dev scripts like pipenv, so create a makefile instead
- Add pytest-cov
- Use tox for testing multiple python versions in CI
- Update README
Update ci workflow
Changes:
- Update config and docs to reference 3.6
- Add backports of dataclasses and datetime.fromisoformat for python_version<"3.7"
- Support both 3.7 and 3.6 usages of undocumented __origin__ attribute on typing objects
- Make github ci run tests for python 3.6 as well
