CI: Add gtk4 package to msys2 environment
Once msys2 environment update #43066 with addition of gtk4 to msys2 is in, we should update also what gets installed for CI test environment. Install gtk4.
As part of #43200, this has also been posted to http://forum.freeciv.org/f/viewtopic.php?f=14&t=92049
Once msys2 environment update #43066 with addition of gtk4 to msys2 is in, we should update also what gets installed for CI test environment. Install gtk4.
As part of #43200, this has also been posted to http://forum.freeciv.org/f/viewtopic.php?f=14&t=92049