New versioning scheme #1604
Description
We’ve decided to change the version numbering scheme from the “semver” approach to a “date-based” approach, since that is better aligned with the practical usage of astroquery and will help us avoid the --pre requirement. Versions will look like <tag number>.YYYYMMDD. For example, if we released one today, it would be 4.20191213, and tomorrow would be 4.20191214. When we increment the tag number, there will be a first tag that is just a bare number. The first one will therefore be 4.
This change will happen once we switch to using https://pypi.org/project/setuptools-scm/ for setup, since that supports setting these date-based versions.