There's a closed pull request on the void-packages repository

postgresql 12.2
https://github.com/void-linux/void-packages/pull/19103

Description:
i've just created a postgres 12.2 version (up from 9.6). I did drop Tcl support from the config, and haven't looked at postgis yet.
It runs fine on my computer (x86_64)

Let me know what you think please.

Removing clusterdb from the client package seemed necessary for the build. When you install postgresql itself, clusterdb is installed