[gnome-2048/arnaudb/wip/gtk4: 29/36] Adapt to AspectFrame API.

[Arnaud B. <arnaudb src gnome org>]

commit b6351ab8a77e1cd9e45fec33b43226f605abea99
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Mon Jul 13 16:54:50 2020 +0200

    Adapt to AspectFrame API.

 src/game-window.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/game-window.vala b/src/game-window.vala
index d12a569..d59368f 100644
--- a/src/game-window.vala
+++ b/src/game-window.vala
@@ -107,7 +107,7 @@ private class GameWindow : ApplicationWindow
         _game.undo_enabled.connect (() => { undo_action.set_enabled (true); });
         _game.undo_disabled.connect (() => { undo_action.set_enabled (false); });
 
-        _frame.add (_game);
+        _frame.set_child (_game);
     }
 
     private void _init_window ()