Doesn't render an image from the `attachments` section

[karnilaev]

Hello,

The library doesn't render files with an image from the attachments section correctly. An example of the file: example.ipynb.zip

Here is how the Visual Studio Code renders the example:

And here is how the nbpreview renders the example:

[jsvine]

Thanks for flagging this, @karnilaev. I agree: notebookjs should handle these, given that they're in the official notebook spec. Do you or does anyone else in the community have interest/availability to contribute this feature?