Made inspectdb used Cursor.description.display_size for CharFields' max_length.

internal_size is size for fixed-size types not for char types.

tests/introspection/tests.py

@@ -132,7 +132,7 @@ class IntrospectionTests(TransactionTestCase):
             )
         self.assertEqual(
             [
-                r[3]
+                r[2]
                 for r in desc
                 if connection.introspection.get_field_type(r[1], r) == "CharField"
             ],