[SF] add missing : after E-Mail

src/gtkgui.glade

@@ -8549,7 +8549,7 @@ Custom</property>
 	      <child>
 		<widget class="GtkLabel" id="label312">
 		  <property name="visible">True</property>
-		  <property name="label" translatable="yes">E-Mail</property>
+		  <property name="label" translatable="yes">E-Mail:</property>
 		  <property name="use_underline">False</property>
 		  <property name="use_markup">False</property>
 		  <property name="justify">GTK_JUSTIFY_LEFT</property>