Updates for latest version of napari

[K-Meech]

• Make sure all the lesson material works for the latest version of napari
• Go through release notes of the last few versions and see if there's anything new we want to mention

[K-Meech]

Now that #125, #124 and #123 are merged, we should be fully compatible with the latest napari + plugin versions.

I'll go ahead and close this issue.