[gnome-sudoku/arnaudb/wip/gtk4: 44/47] Adapt to ListBoxRow API.

[Arnaud B. <arnaudb src gnome org>]

commit e299b4b32aac2642c7067b2815bed50abf8dcac1
Author: Arnaud Bonatti <arnaud bonatti gmail com>
Date:   Wed Sep 23 17:15:45 2020 +0200

    Adapt to ListBoxRow API.

 src/main-menu.vala | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/main-menu.vala b/src/main-menu.vala
index a1aa7cc..159e10b 100644
--- a/src/main-menu.vala
+++ b/src/main-menu.vala
@@ -54,6 +54,6 @@ private class SudokuMainMenuItem : ListBoxRow
         label_widget.can_focus = false;
         label_widget.use_underline = true;
 
-        add (label_widget);
+        set_child (label_widget);
     }
 }