Currently `ECSOperator` propagates `platform_version` parameter either in case `launch_type` is `FARGATE` or there is `capacity_provider_strategy` parameter provided. The case with `capacity_provider_strategy` is wrong. Capacity provider strategy can contain a reference on EC2 capacity provider. If it's an EC2 capacity provider, then `platform_version` should not be propagated to the `boto3` api call. And it's not possible to do so with the current logic of `ECSOperator` because `platform_version` is always propagated in such case and `boto3` doesn't accept `platform_version` as `None`. So in order to fix that `platform_version` should be an independent parameter and propagated only when it's specified, regardless which `launch_type` or `capacity_provider_strategy` is specified. That should also simplify the logic of `ECSOperator`.

I will prepare a PR to fix that.
tests/providers/amazon/aws/operators/test_ecs.py
def test_return_true_on_valid_reason(self):
        self.assertTrue(should_retry(ECSOperatorError([{'reason': 'RESOURCE:MEMORY'}], 'Foo')))
    def test_return_false_on_invalid_reason(self):
        self.assertFalse(should_retry(ECSOperatorError([{'reason': 'CLUSTER_NOT_FOUND'}], 'Foo')))