Also tag releases on Git

[mweinelt]

When packaging a python package for NixOS we prefer to run the tests to make sure our packaging works and we have a smoke test to notice when things go wrong.

The PyPi sdist package does not include tests, which is very reasonable. We would like to fetch the latest version directly from Git, which includes the test. However there are no tags to pinpoint the exact commits that were used for the PyPi releases.

Please add tags, if you can.