Upload first alpha release to pypi

[grzanka]

See #499 and #500

Some alpha releases: https://github.com/DataMedSci/mcpartools/releases

Pypi status: https://pypi.org/project/mcpartools/#history

Actions: https://github.com/DataMedSci/mcpartools/actions/workflows/release.yml

[grzanka]

Seems to work: https://pypi.org/project/mcpartools/0.7.0a4/ , but one needs to check if the package works properly:

pip install mcpartools==0.7.0a4