Updating jupyter install with python3

[josueneo]

While working for Singularity 101 course, I came across these examples and found out the versions are very old, this is an update.

I do not understand why using conda if a pip install is enough to install it, maybe I am missing something. However this is an urgent update since the previous jupyter install was using ubuntu 16 and python 2.7.

[dtrudg]

Also, as a general rule, when creating containers using python.... either...

• Use the distributions own python packages, installing them with the package manage. E.g. apt install jupyter.

-or-

• Use conda

-or-

• Use pip inside a virtual environment, e.g. via venv

When you use pip as root, you can end up installing packages in system locations that can conflict or update over distribution python- packages. Thos distribution python packages may be dependencies of the distros own system admin tools etc. This can cause confusing issues for users who try to take the example as a starting point.