Upgrading Ray and updating simulation_pytorch example

[jafermarq]

This PR updates the Ray version, as dicussed in Issue #1016. I have also used this opportunity to slightly update the simulation_pytorch example by:

• Updating the main to explain what the example is about.
• Exposed a couple of hyperparamters via argparse. I think it is quite relevant to do so for num_client_cpus which controls the number of threads assigned to each client.
• Moved boilerplate code to a new script, utils.py. This is something suggested by @mariaboerner1987 .

[jafermarq]

One point I wanted to ask: do we need a pyproject.toml for this example? One was added a while back.

[danieljanes]

Thanks for the update @jafermarq , looks good! I've approved the PR, but one question: is the switch from 5 to 20 local epochs intentional?

Re pyproject.toml, yes it's needed. We're following the general idea that each example is a self-contained project, pyproject.toml is mainly there to list dependencies. One thing we might do in the future is to have a requirements.txt (in addition to pyproject.toml) to make the examples more approachable for users who do not want to use Poetry.

[jafermarq]

@danieljanes , I see now what you mean about the epochs. I've reverted down to 5 local epochs (making it a more realistic settings). Good catch.