Given the absence of releases or tags in the GitHub repository, I believe you should package it as a vcs pkgbuild [1] with a name like 'ttf-inclusive-sans-git’ and you can remove the commit as well.
The versioning (e.g., 2.13) appears to be derived from the Google scaffolding template used to set up the repository. I defer to more experienced individuals for further input.

[1] /usr/share/pacman/PKGBUILD-vcs.proto