fix: avatar_storage: Find correct node for texture
While the previous code worked in Gtk 4.18, in 4.20 we receive an arbitrary cached rendernode. Thus, traverse the scene graph to find the desired texture node.
See https://gitlab.gnome.org/GNOME/gtk/-/commit/0c7bbb079476c9fcce974c8a7c2d026b3e3047a9
Tested with a locally compiled Gtk 4.20.1 branch.
Fixes: #12473 (closed)
Edited by mesonium