Add a JSON Validation Step to Testing

[visch]

To help prevent an issue like #72 adding a validation step in our testing process would be very helpful. In the case for #72 I added the custom field that caused the issue and ran the tap with a target that validates the json (target-jsonl) to hit the error.

The only issue is that as clickup adds new features we'd have to update our data to match the new features to be sure the tap would continue to work.