Project:GNOME/GNOME bumping notes

Notes on why I didn't bump outdated GNOME packages:


 * - Depends on -6.0.
 * - Nothing depends on libxmlpp:5.
 * - Needs meson port.
 * Build system in pretty terrible shape. See https://gitlab.gnome.org/GNOME/libgda/-/merge_requests/198
 * - Nothing depends on v3.9 that doesn't also support v2.9.
 * Build system is a mess and package is not actively maintained upstream.
 * - v1.0 drops deprecated APIs; unsure if consumers are affected.