DOI (digital object identifier) for GEOS

[Daniel Baston]

> Zenodo integration on the libgeos/geos github project?

I looked into this for another project and hesitated about giving
Zenodo access to my GitHub account. There's also a GitHub Action for
this, but my experience is that actions triggered by releases are hard
to maintain unless you're releasing very frequently.

I think our releases are infrequent enough that I can manually upload
them if we want to. From my end, the value is more in the "concept"
DOI than in opening another distribution channel and having individual
releases be citable.

Dan