Wrong shaded contours in the PostProcessing notebook

[thjsal]

Wrong contours are shown shaded in the current Post-processing tutorial after code block 16 (blue contours are shown red shaded instead of red contours).

This is because the plotting is using outdated input parameters for the latest GetDist. One should replace

shaded=True,
shade_root_index=-1,

with

shaded=-1,

to get it working.

(see here: cmbant/getdist@d070091)