Use tags for versioning

[has2k1]

setuptools_scm

With tagged versioning you have each commit as a distinct version and can have different documentation for stable & development.

[machow]

In case it's useful -- there's a github action job to deploy to PyPI in pins here!: https://github.com/rstudio/pins-python/blob/main/.github/workflows/ci.yml#L257-L276

[isabelizimm]

closed with #86