Small correction to make IGNNK_U_Central_missing.ipynb work

[dd-the-dd]

The udata_sim.joblib was save with an older version (0.21) of scikit-learn which was using scikit.external.joblib which is deprecated since (0.23). I saw a solution to upload the data with the old version and then save the weight directly with joblib. Then it work well on the latest version of scikit-learn.

If you do not want to keep that repository up to date, it would be interesting to share the actual version of each library so we can use it right away :)

I also had to typpo in one of the variable in the jupyter.

Thanks for the content, it is a really interesting project :)

[dd-the-dd]

The result of IGNNK are less better than all the other results so I suspect the weights was not good, I'm retraining the model right now to fix that, I may push it back if it is working