plot.box - deprecated pandas function call

[l-welder]

In the box plot function, panda's set_categories function is called:

pyam/pyam/plotting.py

Line 714 in 525ede9

df[by].cat.set_categories(list(palette), inplace=True)

However, the inplace parameter of the set_categories was removed in pandas >= 2.0 (see pandas_<2, pandas_>=2).

This leads to an issue when calling the box plot function with a by parameter when the following if call triggers:

pyam/pyam/plotting.py

Line 710 in 525ede9

if "palette" not in kwargs and "color" in rc and by in rc["color"]:

A simple fix is to replace the line with: df[by].cat = df[by].cat.set_categories(list(palette)).