This release makes minor changes to the metadata, ensures tests run correctly from sdist
packages, and uses non-vendored versioneer to version itself.

With thanks to Simão Afonso for contributions.

* FIX: Include pyproject.toml in MANIFEST.in by @effigies (#326)
* STY: Appease flake8 by @simaoafonso-pwt (#327)
* MNT: Version versioneer with versioneer by @effigies (#323)
* CI: Build package and push to PyPI on tag by @effigies (#328)
* CI: Explicitly test sdist by @effigies (#329)