Bumped hdbscan version to 0.8.29

[datlife]

Hi hdbscan maintainer(s),

This PR would prepare for the release to PyPi. I also notice that README.md contains old documentation on how to run tests. I believe this package no longer use nose in favor of pytest. However, it can be in a separate PR.

I think there are two remaining action items from maintainer:

• tag and branch out a new release branch for 0.8.29
• launch a new Github Workflow to publish a new release to PyPi.

Please let me know if there is something I can help with.

Regards,
Dat