add padding to help/continue button box (#914)

make it consistent with do not show checkbox padding

Author: timfeierabend

usr/share/linuxmint/mintupdate/kernels.ui

@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="UTF-8"?>
-<!-- Generated with glade 3.38.2 -->
+<!-- Generated with glade 3.40.0 -->
 <interface>
   <requires lib="gtk+" version="3.18"/>
   <object class="GtkWindow" id="window">
@@ -520,6 +520,7 @@
                   <packing>
                     <property name="expand">False</property>
                     <property name="fill">True</property>
+                    <property name="padding">3</property>
                     <property name="position">1</property>
                   </packing>
                 </child>