JupyterLab 3.0 and other updates

[romainx]

Upgrade to JupyterLab 3.0.x as described in #1207 and other upgrades.

• base-notebook
  • Changed: Bump ubuntu
  • Changed: Bump jupyterlab -> Fixes JupyterLab 3.0 #1207 and fixes Problem with Restart kernel and run all cells for R and Julia kernels in datascience-notebook? #1167
• scipy-notebook
  • Changed: Bump dask
  • Changed: Bump ipympl
  • Changed: Bump pandas
  • Changed: Bump scipy
  • Removed: Jupyter Extension management through npm and jupyter labextension.
    It is not necessary anymore, and I have checked that both ipywidgets and matplotlib are working with JupyterLab and Jupyter. It speeds up the build time.
  • Removed: Skip extension test, see limitations below for detail
• datascience-notebook
  • Changed: Bump rpy2
• tensorflow-notebook
  • Changed: Bump tensorflow

Even with the limitations (Bokeh extension is the only regression) listed below, I think it is reasonable to merge it.

Limitations

Bokeh extension not available

Bokeh extension is not ready for JupyterLab 3.0.x see bokeh/bokeh#10569.

Check extension

jupyter labextension check seems to not work anymore. We should create an issue in the upstream repo.

# Installation don't need to use node now
conda install --quiet --yes 'ipywidgets=7.6.*'

# Preparing transaction: ...working... done
# Verifying transaction: ...working... done
# Executing transaction: ...working... Enabling notebook extension jupyter-js-widgets/extension...
      - Validating: OK
      
# List extensions, everything is OK
jupyter labextension list

# JupyterLab v3.0.5
# /opt/conda/share/jupyter/labextensions
#        @jupyter-widgets/jupyterlab-manager v3.0.0 enabled OK (python, jupyterlab_widgets)

# However, the check does not work
jupyter labextension check @jupyter-widgets/jupyterlab-manager

# @jupyter-widgets/jupyterlab-manager: X

Warning at start

There is a warning at the start that seems related to this configuration c.ServerApp.open_browser = False in jupyter_server_config.py, see jupyterlab/jupyterlab#9360

# [W 2021-01-22 08:14:06.693 ServerApp] No web browser found: could not locate runnable browser.

[mathbunnyru]

I made some small notes, but I approve the change as it is.

[mathbunnyru]

💪

[romainx]

As it has been reviewed by @mathbunnyru, I'm merging it. It's time to take the plunge. We will manage issues if any 🙄.