Fix devcontainer setup

[jorisSchaller]

What does this PR do?

Fixes #4298
This PR fix the dev container setup.
It

• bumps the python version from 3.7 to 3.12
• Install scikit-learn with the correct name (scikit-learn and not sklearn)
• Correct the flax path

Checklist

• This PR fixes a minor issue (e.g.: typo or small bug) or improves the docs (you can dismiss the other
  checks if that's the case).
• This change is discussed in this issue
• The documentation and docstrings adhere to the
  documentation guidelines.
• This change includes necessary high-coverage tests.
  (No quality testing = no merge!)

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