Subject: bug#79409: 31.0.50; project.el uses define-completion-category but depends on 26.1

From: Daniel Mendler <[email-masked]>
Date: Mon, 08 Sep 2025 15:49:49 +0200

Since a few days ago project.el uses define-completion-category which is
not yet available on old Emacs versions. project.el is published on ELPA
and depends on Emacs 26.1.

See also https://old.reddit.com/r/emacs/comments/1nblwbl/suddenly_everything_wants_definecompletioncategory/