Add publication date

[tmorrell]

Example DOI

https://api.crossref.org/works/10.5194/egusphere-2024-2578

I'm wondering if CrossRef is cleaning up their date handling. This DOI has none of the dates we traditionally mapped, and has a plain publication date. We don't map the plain publication date, and we should.

irdmtools/crossref.go

Line 441 in 11acb2e

}

It's probably safest if we put it here after published online.

[rsdoiel]

Fixed in upcoming v0.0.88 release.