Fix CI Failures

[Darshan808]

This PR fixes CI failures in JupyterLab downstream tests and test_examples.

• test_examples: Adding a license to pyproject.toml resolves the issue.
• JupyterLab downstream test: Followed Mike’s suggestion:

move this block back to sync start_app and document that this message banner will be shown before the async extensions are registered.

One thing I wasn't sure about—where should we document the message banner shown before async extensions are registered? And also I think we need to show some message after the async extensions are registered. Let me know your thoughts!

[krassowski]

where should we document the message banner shown before async extensions are registered

Maybe under the same section added in jupyter-server#1417 ("Starting asynchronous tasks from an extension")

[Darshan808]

@Zsailer Could you approve the workflow or review the code? 😊

[Zsailer]

Amazing work @Darshan808 and @krassowski. Thank you, folks, for jumping in here!

[Zsailer]

The Actions here are outdated. Let's merge this and let the tests run in the upstream PR. If we need to iterate in another PR here, that's totally fine.