Update to JupyterLab 3.3.0

[jtpio]

Update to the JupyterLab 3.3.0rc0 packages, to help catch potential issues if any.

[github-actions]

👈 Launch a Binder on branch jtpio/retrolab/lab-3-3

[jtpio]

Looks like the notebook:create-new command is not registered by default anymore:

[jtpio]

Some toolbar positioning to fix:

[jtpio]

The same trick was added on the main branch (targeting lab 4.0) in #319.

However for RetroLab 0.3.x we should find a better way to handle this.

[jtpio]

Without the workaround (commit 978fef7)

Binder: https://mybinder.org/v2/gh/jtpio/retrolab/978fef7?urlpath=retro

With the workaround (commit dd750da)

Binder: https://mybinder.org/v2/gh/jtpio/retrolab/dd750da?urlpath=retro

As the next step I will be looking into dropping the workaround, and use a similar approach as in JupyterLab to register toolbar widgets:

https://github.com/jupyterlab/jupyterlab/blob/b27408b1bf70bad1cb519fc8993d0dc03f56362e/packages/notebook-extension/src/index.ts#L926-L939

[jtpio]

Looking better now.

Next steps:

• wait for 3.3 final (JupyterLab 3.3 Release jupyterlab#11643)
• update the @jupyterlab packages to 3.3 final here
• merge this PR
• release RetroLab

[jtpio]

Now updated to the 3.3.0 final packages.