- Add unit tests for api.py module
- Add dev packages to pyproject.toml

- Add noxfile.py with lint, unit_tests, mypy sessions
- Add dev-packages for linting, typing
- Add .flake8, mypy.ini configurations files

- Add github commit.yml, coverage.yml pipelines with testing, linting and code coverage
- Add unit tests/coverage reports to .gitignore
- Add new code coverage badge to README.md, add PyPI badge logo
- Add coverage nox session, add type annotations to noxfile.py
- Add dev-dependencies to pyproject.toml:
  - codecov 2.1.12
- Change single-sourcing package version (anac/core/__init__), using standard importlib.metadata library (it's possible from Python 3.8) instead of pkg_resources library
- Change import statemenets (groups and order) with flake8-import-order plugin and import-order-style = google .flake8 option. Black reformatting with max-line-length = 88 option:
  - anac/__init__.py
  - anac/core/api.py
  - anac/core/endpoint.py
  - anac/core/exceptions.py
  - noxfile.py
  - tests/unit/test_api.py
- Remove B9 .flake8 option (flake8-bugbear option)