pdp_interact_plot is incompatible with matplotlib 3.0.0

[rexmadden]

In ml1/lesson2-rf_interpretation.ipynb

Since we don't pin a matplotlib version, mine was updated to 3.0.0. This caused an issue because https://matplotlib.org/api/_as_gen/matplotlib.pyplot.clabel.html does not take contour_label_fontsize

After going back to 2.2.3, it was fine.

Thanks for your comment..!

1. How did you downgrade it to version 2.2.3 ?
2. When you downgrade, did the other functions like 'pdp.pdp_interact' effect (i.e did you have to change anything)?

[rexmadden]

I just pegged the version in the environment file. Everything else should work file