[ENH] Refactor `OpenMLEvaluation` to Use Dataclass

[SimonBlanke]

As stated in the file: "A lot of this class is automatically handled by a dataclass". This could make the implementation cleaner (less boilerplate). So we should go for a dataclass implementation for this class.

[rohansen856]

I would be working on this issue. PR in progress. Thanks.

[sunilkumar2170]

Hi @fkiraly,

Thanks for the update. I see that this issue already has an active PR and related commits.

I’d be happy to contribute to other refactoring or dataclass-related issues in openml-python.
Could you please suggest any open issues suitable for a new contributor?

Thanks!