Update message on ErrorDialog

Author: romjerome

lxml/lxmlGramplet.py

@@ -465,7 +465,7 @@ def ParseXML(self, tree, filename):
             ErrorDialog(_('Missing header'), _('Not a valid .gramps.\n'
                                     'Cannot run the gramplet...\n'
                                     'Please, try to use a .gramps\n'
-                                    'generated by Gramps 4.x.'))
+                                    'generated by Gramps 5.1.'))
             LOG.error('header missing')
             return