[gnome-builder] meson-templates: bump GTK requirement version

[Christian Hergert <chergert src gnome org>]

commit 703a66a276f28b496122c36b1f802ca061932849
Author: Christian Hergert <chergert redhat com>
Date:   Mon Mar 9 14:42:00 2020 -0700

    meson-templates: bump GTK requirement version
    
    This should be 3.24, since that is our mostly recent release series and
    we very much want people using that.

 src/plugins/meson-templates/resources/src/window.ui | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
---
diff --git a/src/plugins/meson-templates/resources/src/window.ui 
b/src/plugins/meson-templates/resources/src/window.ui
index 1263098c1..7522b7229 100644
--- a/src/plugins/meson-templates/resources/src/window.ui
+++ b/src/plugins/meson-templates/resources/src/window.ui
@@ -1,6 +1,6 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <requires lib="gtk+" version="3.20"/>
+  <requires lib="gtk+" version="3.24"/>
 {{if language == "c++"}}
   <object class="GtkHeaderBar" id="headerbar">
     <property name="can_focus">False</property>