For that I need to add package into debian-stable Docker so I follow guideline in .gitlab-ci/README.md and build a new docker. For pushing it in registry.gitlab.gnome.org/gnome/glib/debian-stable I create a personnal access token:
You cannot push to the GLib registry yourself, because you’re not one of the GLib maintainers. At most, you can push to the registry of your personal fork. For that, you’ll have to extract the repository location and modify the run-docker.sh script—or simply call the command that the script calls, but with a different repository URL.
I don’t think you have access to the registry, at all (i.e. not only GLib’s part). The correct course of a actions would probably be to get your work done for https://gitlab.gnome.org/GNOME/glib/-/issues/2046, submit a MR for it and then it’ll get pushed to the official registry when you manage to get it merged (after review).