hello! I'm brand new to prefect 2 and I'm running into some issues using the ECS block. I've created an ECS block but whenever I try to add any labels at all I get an error when trying to load said block. I've attached a screenshot of what I see in the UI and the error I get when the "Labels" field has a value in it. How can I create an ECS block that with these fields filled out that passes validation when trying to load that block?