Update to JupyterLite 0.2

[jtpio]

Update to the latest stable version of JupyterLite, which is based on JupyterLab 4 and Jupyter Notebook 7.

Closes #150
Closes #151

[rclement]

Thanks @jtpio! So jupyterlab-webrtc-docprovider is not needed anymore? Has it been integrated directly into Jupyterlab?

[jtpio]

Right, unfortunately this extension has not yet been updated for JupyterLite 0.2 (based on JupyterLab 4): jupyterlite/jupyterlab-webrtc-docprovider#16

Mostly because the whole RTC stack has changed quite a bit between JupyterLab 3.5 and JupyterLab 4.

So maybe we can keep it commented for now in the Pipfile to keep to track of it?

[jtpio]

Also for now jupyterlab-webrtc-provider is more of a proof-of-concept rather that something that can be used in production. It's not working super well (duplicated content, errors when syncing the documents...).

[rclement]

Closed in favor of #194