[2.2.x] Fixed #33082 -- Fixed CommandTests.test_subparser_invalid_option on Python 3.9.7+.

Thanks Michał Górny for the report.

Backport of 50ed545e2f from main.

tests/user_commands/tests.py

@@ -218,7 +218,7 @@ class CommandTests(SimpleTestCase):
         self.assertIn('bar', out.getvalue())
 
     def test_subparser_invalid_option(self):
-        msg = "Error: invalid choice: 'test' (choose from 'foo')"
+        msg = "invalid choice: 'test' (choose from 'foo')"
         with self.assertRaisesMessage(CommandError, msg):
             management.call_command('subparser', 'test', 12)