[gtranslator] Add missing property to show menmonic properly

[Daniel Mustieles García <dmustieles src gnome org>]

commit 3dcc1e27d8a5915b1abb6a32a1d275963b7772a5
Author: Daniel Mustieles <daniel mustieles contractor bbva com>
Date:   Fri Mar 29 12:06:40 2019 +0100

    Add missing property to show menmonic properly

 src/gtr-languages-fetcher.ui | 1 +
 1 file changed, 1 insertion(+)
---
diff --git a/src/gtr-languages-fetcher.ui b/src/gtr-languages-fetcher.ui
index 76124b30..b9e47a28 100644
--- a/src/gtr-languages-fetcher.ui
+++ b/src/gtr-languages-fetcher.ui
@@ -202,6 +202,7 @@
                 <property name="can_focus">True</property>
                 <property name="receives_default">False</property>
                 <property name="draw_indicator">True</property>
+               <property name="use_underline">True</property>
               </object>
               <packing>
                 <property name="left_attach">1</property>