Use DermaMNIST-C

[henrykrumb]

Abhishek et al. found several flaws in DermaMNIST, such as improper resizing and data leakage:

https://www.nature.com/articles/s41597-025-04382-5

Not sure if this explains the bad performance of NCALab on this dataset, but it definitely makes sense to try DermaMNIST-C instead:

https://github.com/kakumarabhishek/Corrected-Skin-Image-Datasets