[gtksourceview] styleschemechooserwidget: tweak grid spacing

[Christian Hergert <chergert src gnome org>]

commit 79888d830aa14fd4d7419a9cc882a4295bbd44ee
Author: Christian Hergert <chergert redhat com>
Date:   Sun Oct 17 13:41:25 2021 -0700

    styleschemechooserwidget: tweak grid spacing

 gtksourceview/gtksourcestyleschemechooserwidget.ui | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)
---
diff --git a/gtksourceview/gtksourcestyleschemechooserwidget.ui 
b/gtksourceview/gtksourcestyleschemechooserwidget.ui
index 1c3d998e..d45ae3ec 100644
--- a/gtksourceview/gtksourcestyleschemechooserwidget.ui
+++ b/gtksourceview/gtksourcestyleschemechooserwidget.ui
@@ -1,9 +1,11 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <interface>
-  <requires lib="gtk+" version="3.98"/>
+  <requires lib="gtk" version="4.0"/>
   <template class="GtkSourceStyleSchemeChooserWidget" parent="GtkWidget">
     <child>
       <object class="GtkGrid" id="grid">
+        <property name="column-spacing">12</property>
+        <property name="row-spacing">6</property>
       </object>
     </child>
   </template>