v0.22.1

Packaging and citation metadata only. No code changes from 0.22.0.

Changed

• pyproject.toml's authors field said just Michael, which is what PyPI
  would have shown as the author. It now names K.-Michael Aye.

• New CITATION.cff, which drives GitHub's "Cite this repository" button, and
  new .zenodo.json, which overrides the creators Zenodo otherwise infers from
  the repository's contributor statistics. Both carry ORCID
  0000-0002-4088-1928 in the form each
  format requires: CFF takes the full https://orcid.org/ URL, Zenodo's API
  takes the bare identifier.

These landed after the v0.22.0 tag, so this patch release exists to keep the
tag, the published artefact and the Zenodo record pointing at the same thing.