Fixes to prepare the code for pandas 2.0
Created by: scarlehoff
Fixes #1722 (closed), at least such that the test pass in my computer.
Note, right now we are "blocked" in pandas < 2.0 due to eko
. But we might as well fix these small things as we find them. In this case they removed a keyword and change some defaults https://pandas.pydata.org/docs/reference/api/pandas.DataFrame.groupby.html
Since pandas 2.0 changed a bunch of defaults we will have to look very careful at many reports when we decide to make the change... so for now I'm happy that we are blocked at 1.X.