See ../ai/RELEASE.md for the actual release process
(pre-release checks, versioning, make tag/make dist, the stable
pseudo-version dance, PGXN upload). This file covers only what's genuinely
specific to count_nulls.
../ai/RELEASE.md step 3 covers the general PGXN fact that a distribution's
version (META.in.json's top-level version) and an extension's version
(<ext>.control's default_version) are separate numbers that can differ —
that's not specific to count_nulls. What's specific here is that count_nulls
has actually made use of it: 0.9.7 on PGXN (2017-01-26) was a
distribution-only bump (packaging/CI fixes, no SQL changes) — the extension
version stayed at 0.9.6, unchanged since 2016. 0.9.7 the extension
version has never existed.