PyPi

Preparation:

update all help files (img-help -f markdown -o plugins -t "imgstats plugins" -i README.md -l INFO)
increment version in setup.py
add new changelog section in CHANGES.rst
align DESCRIPTION.rst with README.md
commit/push all changes

Commands for releasing on pypi.org (requires twine >= 1.8.0):

find -name "*~" -delete
rm dist/*
python3 setup.py clean
python3 setup.py sdist
twine upload dist/*

Github

Steps:

start new release (version: vX.Y.Z)
enter release notes, i.e., significant changes since last release
upload image-dataset-converter-imgstats-X.Y.Z.tar.gz previously generated with setup.py
publish