4.21.0 (unstable) 2025-11-14

Gtk:
* Application: Add save(), forget(), property_support_save(),
  signal_restore_window(), signal_save_state(), signal_restore_state().
* ApplicationWindow: Add signal_save_state().
* CssProvider: Add property_prefers_reduced_motion().
* Settings: Add property_gtk_interface_reduced_motion().
* SymbolicPaintable: Add snapshot_with_weight().
* New classes: AccessibleHyperlink, AccessibleHypertext, Svg, SvgErrorExtra.
* New enums: ReducedMotion, RestoreReason, SvgError.
  (Kjell Ahlstedt)

Build:
* Require gtk4 >= 4.21.1
  (Kjell Ahlstedt)