GTK3: status_icon#set_tooltip_text is missing

[talex5]

GTK replaced gtk_status_icon_set_tooltip with gtk_status_icon_set_tooltip_{text,markup}:

https://gitlab.gnome.org/GNOME/gtk/commit/d06e67023cf779f7af3e508de64ac1316ec08508

However, it appears that lablgtk simply deleted the method (in dc9aaad).

[garrigue]

Thank you for the report.
Pull-request is welcome (if this is just a change in the props file).