gtkfontchooserwidget: Reduce the size request

This helps GtkfontChooserDialog fitting in mobile phone screens.

gtk/ui/gtkfontchooserwidget.ui

@@ -70,8 +70,8 @@
                     <child>
                       <object class="GtkScrolledWindow" id="list_scrolled_window">
                         <property name="visible">1</property>
-                        <property name="width-request">400</property>
-                        <property name="height-request">300</property>
+                        <property name="width-request">300</property>
+                        <property name="height-request">50</property>
                         <property name="can-focus">1</property>
                         <property name="hexpand">1</property>
                         <property name="vexpand">1</property>