[gtkmm] Created tag 3.24.6

[Kjell Ahlstedt <kjellahl src gnome org>]

The unsigned tag '3.24.6' was created.

Tagger: Kjell Ahlstedt <kjellahlstedt gmail com>
Date: 1651504485 +0200

    3.24.6

Changes since the last tag '3.24.5':

Chun-wei Fan (1):
      build: Support Visual Studio 2022

Kjell Ahlstedt (7):
      SizeGroup demo: Derive from Gtk::Window instead of Dialog
      docs/reference/Doxyfile.in: Remove obsolete entry
      treeiter.hg: Declare TreeValueProxy copy constructor =default
      meson.build: Specify 'check' option in run_command()
      meson.build: Check if Perl is required for building documentation
      Gtk::Object::_release_c_instance(): Unref orphan managed widgets
      3.24.6