[vala] (6 commits) Non-fast-forward update to branch wip/gtk4

[Rico Tzschichholz <ricotz src gnome org>]

The branch 'wip/gtk4' was changed in a way that was not a fast-forward update.
NOTE: This may cause problems for people pulling from the branch. For more information,
please see:

 https://wiki.gnome.org/Git/Help/NonFastForward

Commits removed from the branch:

  1cef546... vapi: Add unstable bindings for gtk+-4.0 3.89+

Commits added to the branch:

  c80be97... gio-unix-2.0: Fix "g_unix_mount_at" binding (*)
  8b5e415... gio-unix-2.0: Add "g_unix_mounts_for" binding (*)
  ab31efd... glib-2.0: Add "g_utf8_make_valid" binding (*)
  b18a779... glib-2.0: Some nullable arguments in GLib.Test.* (*)
  f52b484... gdk-pixbuf-2.0: Use metadata instead of custom defintions f (*)
  79ca84a... vapi: Add unstable bindings for gtk+-4.0 3.89+

(*) This commit already existed in another branch; no separate mail sent