This catches downstream consumers of neovim off-guard when trying to use
neovim in an esoteric environment not tested in our own CI.
Closes https://github.com/neovim/neovim/issues/22932
(cherry picked from commit 0256b67e89)
Having to specify CI_BUILD for every CI job requires boilerplate. More
importantly, it's easy to forget to enable CI_BUILD, as seen by
8a20f9f98a. It's simpler to remember to
turn CI_BUILD off when a job errors instead of remembering that every
new job should have CI_BUILD on.
This will allow users to use AppImageUpdate to update their AppImage.
It requires publishing the created zsync file alongside the appimage
file for the releases.
