fix: Add missing bracket in test assertion

Author: chalmerlowe

tests/unit/test_spanner.py

@@ -1077,7 +1077,7 @@ def test_transaction_for_concurrent_statement_should_begin_one_transaction_with_
         expected_requests = [
             self._batch_update_expected_request(),
             self._batch_update_expected_request(begin=False),
-
+        ]
 
         actual_requests = [call.kwargs["request"] for call in call_args_list]
         self.assertCountEqual(actual_requests, expected_requests)