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
self.set_up_operator()
        self.mock_context = mock.MagicMock()
    def test_init(self):
        assert self.ecs.region_name == 'eu-west-1'
        assert self.ecs.task_definition == 't'
        assert self.ecs.aws_conn_id is None
        assert self.ecs.cluster == 'c'
        assert self.ecs.overrides == {}
        self.ecs.get_hook()
        assert self.ecs.hook == self.aws_hook_mock.return_value
        self.aws_hook_mock.assert_called_once()
    def test_template_fields_overrides(self):