#111 Update environment to 2024.

@jediaz

Essentially modifications to ensure I'm able to run the notebooks properly.

Basically:

• Anaconda environment had to be modified, with a specification of strict gcc version to support C++ 14 and C++17 standards.
• Jupyter extensions are unfortunately no longer supported (and my quick attempts to use nbclassic didn't work as expected for them). So I have switched back to JupyterLab (but we can no longer update the table of contents automatically )
• Apparently now we need to give a token to run a notebook; the commands have been updated and the README updated as well.
• I have changed the name of conda environment and username in Docker images to make them shorter.