Review Python packages installed in user image

[alimanfoo]

This issue is a catch-all for reviewing the list of Python packages and their versions that we install into the user image. Various parts to this...

• [ ] Currently bokeh is not working in jupyterlab. I believe to get it working requires a bokeh_jupyterlab extension to be installed. xref https://github.com/bokeh/bokeh/issues/6700
• [ ] Zarr and several other packages are pinned at dev versions, probably a reflection of ongoing dev work on pangeo, we should fall back to release versions where we can. Also two versions of xarray installed.
• [ ] Strip out unnecessary geo-related packages.
• [ ] Add in all packages in agam-report-base conda and pypi lists.
• [ ] Ensure can download notebook as PDF.

[alimanfoo]

I added some comments on the dockerfile commit https://github.com/malariagen/jupyterhub/commit/3fa889b4bb55b0f17aa0ef1f00680020768e21ec - I can make a PR to address them, no rush.

One question I had, @slejdops maybe you could find out, two packages nbserverproxy and xgcm are currently installed from git, but do they need to be? Could we install from a release version?