Bump rust-polars to 0.41

[etiennebacher]

I want to start checking empty dots after this PR (meaning that we don't release a new version just after this PR)

---

TODO:

• uncomment commented tests for map_batches()
• tests for statistics options in sink/write_parquet

[eitsupi]

Thanks for working on this!

Looking at the polars repository it looks like a patch version is planned (pola-rs/polars#17133 (comment)), so perhaps we should wait for that before merging (or release).

[etiennebacher]

Sure, there's still plenty of work to do anyway but I'll add this in the top post, thanks

[etiennebacher]

@eitsupi everything passes except the README because of this bug: pola-rs/polars#17308

Let's see how it is handled upstream, there might be another minor release of rust-polars that we could integrate in this PR.

[eitsupi]

Thanks for the great work!
A few minor comments.

[etiennebacher]

Thanks for the review. The issue reported upstream has been fixed so later today I will update the rust-polars version to unreleased (unless 0.41.3 is released in the meantime).

[etiennebacher]

@eitsupi I'll try to deal with checking dots later in the week, and then I think we can release 0.18