I installed v12.2-4 on my Windows VM, launched StackBuilder and upgraded to version v12.9-1 (the latest stable release) and the registry entry was updated. I've attached the screenshots.
Please also note that Tenable should really *not* be checking what version is installed in this way, as that info is intended for the installer (and pgAdmin, and other similar apps) for internal use and non-security related service discovery. It is easily possible for a user to update parts of the PostgreSQL installation without changing that registry value, e.g. by unpacking the zipped binary distribution over an existing installation.
Any security scanner worth it's salt should be examining the VERSIONINFO resource in postgres.exe to see what is actually installed (or connecting to the database server and asking it, but that might be harder).
