tests: fix scheduler test

[achille-roussel]

Fix for this error, not sure why it didn't occur in CI, I may have a different version of protobuf.

================================================ FAILURES ================================================
______________________ TestOneShotScheduler.test_resume_after_gather_one_at_a_time _______________________

self = <tests.dispatch.test_scheduler.TestOneShotScheduler testMethod=test_resume_after_gather_one_at_a_time>

    def test_resume_after_gather_one_at_a_time(self):
        @durable
        async def main():
            return sum(await call_concurrently("a", "b", "c", "d"))

        output = self.start(main)
        calls = self.assert_poll_call_functions(output, ["a", "b", "c", "d"])
        for i, call in enumerate(calls):
            output = self.resume(
                main,
                output,
                [CallResult.from_value(i, correlation_id=call.correlation_id)],
            )
            if i < len(calls) - 1:
>               self.assert_empty_poll(output)

tests/dispatch/test_scheduler.py:159:
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
tests/dispatch/test_scheduler.py:288: in assert_empty_poll
    self.assertEqual(poll.calls, [])
E   TypeError: Can only compare repeated composite fields against other repeated composite fields.