[swell-foop/ricotz/vala] Reference of [GtkChild] fields is handled by GtkBuilder, type must be unowned

[Rico Tzschichholz <ricotz src gnome org>]

commit d0f22f765d3d2236a565358670355934e125e101
Author: Rico Tzschichholz <ricotz ubuntu com>
Date:   Wed Mar 17 11:03:03 2021 +0100

    Reference of [GtkChild] fields is handled by GtkBuilder, type must be unowned

 src/window.vala | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)
---
diff --git a/src/window.vala b/src/window.vala
index 3235a25..04ea1f9 100644
--- a/src/window.vala
+++ b/src/window.vala
@@ -22,9 +22,9 @@ using Gtk;
 [GtkTemplate (ui = "/org/gnome/SwellFoop/ui/swell-foop.ui")]
 private class SwellFoopWindow : ApplicationWindow
 {
-    [GtkChild] private HeaderBar    headerbar;
-    [GtkChild] private Box          main_box;
-    [GtkChild] private MenuButton   hamburger_button;
+    [GtkChild] private unowned HeaderBar    headerbar;
+    [GtkChild] private unowned Box          main_box;
+    [GtkChild] private unowned MenuButton   hamburger_button;
 
     private GLib.Settings settings;