Use polars instead in examples

[adrinjalali]

Modern examples at this point should be using polars instead really, instead of pandas. For instance, here: https://github.com/probabl-ai/skore/blob/main/examples/plot_01_getting_started.py

[thomass-dev]

I have nothing against, but what are the cons of using pandas in the example notebooks?
Can we use both instead?

[adrinjalali]

At this point using polars on new code just seems old school since when starting a new project, we'd recommend users to start with polars anyway. It has better API and is faster, and narwhals basically mirrors its API.

[thomass-dev]

At this point using polars on new code just seems old school

*pandas, right?

For a better adoption, i would recommend to put example of both pandas and polars, and add a comment to recommend polars.