* add: configure files (setup.py->setup.py+setup.cfg+pyproject.toml)
* add: __download_url__
* format with black and isort
* fix: flake8 section in setup.cfg
* add: E501 to flake ignore
* fix: metadata.name does not accept attr
* fix: merge __version__.py into __init__.py
* fix: flake8 errors in tests/
* fix: datetime.datetime -> datetime
* fix: banner
* fix: ignore W605 for banner
* fix: way to install deps in CI
* add: versem to setuptools
* fix: drop python<=3.6 (#126) from package and CI
