Version tags

Hi,

version `0.2.8` has a critical fix for python >= 3.9 (regarding the json encoder), but it hasn't been pushed to pypi.

@PascalLesage It would be great if you could:

- [ ] push version 0.2.8 to pypi
- [ ] tag the repository with 0.2.8 in master branch so that other consumers can specify a version to install from source

:D 