Fix a style issue raised in CI

RUF059 Unpacked variable `error` is never used

Author: gudnimg

jsonschema/tests/test_exceptions.py

@@ -321,7 +321,7 @@ def test_boolean_schemas(self):
 
     def test_one_error(self):
         validator = _LATEST_VERSION({"minProperties": 2})
-        error, = validator.iter_errors({})
+        validator.iter_errors({})
         self.assertEqual(
             exceptions.best_match(validator.iter_errors({})).validator,
             "minProperties",