[1.11.x] Fixed #28176 -- Restored the uncasted option value in ChoiceWidget template context.

Backport of 221e6e1817 from master

tests/forms_tests/widget_tests/test_select.py

@@ -351,6 +351,12 @@ class SelectTest(WidgetTest):
         )
         self.assertEqual(index, 2)
 
+    def test_optgroups_integer_choices(self):
+        """The option 'value' is the same type as what's in `choices`."""
+        groups = list(self.widget(choices=[[0, 'choice text']]).optgroups('name', ['vhs']))
+        label, options, index = groups[0]
+        self.assertEqual(options[0]['value'], 0)
+
     def test_deepcopy(self):
         """
         __deepcopy__() should copy all attributes properly (#25085).