Sort selection strings without key function

The selection is a list of string so we can sort as-is.

Closes #14883
(grafted from 2d7c2466ae0eda5dc670cc8fd2ee5b386fb704ab)

--HG--
branch : 8.0

tryton/tryton/gui/window/view_form/view/screen_container.py

@@ -2,7 +2,6 @@
 # this repository contains the full copyright notices and license terms.
 import datetime
 import gettext
-import operator
 
 from gi.repository import Gdk, GLib, GObject, Gtk
 
@@ -629,7 +628,7 @@ class ScreenContainer(object):
                 elif field['type'] in ['selection', 'multiselection']:
                     selections = [x[1] for x in field['selection']]
                     if field.get('sort', True):
-                        selections.sort(key=operator.itemgetter(1))
+                        selections.sort()
                     entry = Selection(tuple(selections))
                     entry.set_vexpand(True)
                 elif field['type'] in ('date', 'datetime', 'time'):