Bug#941078: transition: postgresql-12

[Christoph Berg]

Re: Paul Gevers 2019-11-13 <d6bf0502-e66d-0853-fff6-ae4c4601b...@debian.org>
> Scheduled.

Thanks!

Not sure why my last list missed a few, but here's three more:

postgresql-multicorn
pldebugger
first-last-agg

Christoph