The function usage has been updated for calculating grouped means

[nkandhari]

In the chapter, Data analysis in Python (https://github.com/MonashDataFluency/python-workshop-base/blob/master/workshops/docs/modules/working_with_data.md), the few bits have been updated and needs to be updated in the material too.

Under the heading: Groups in Pandas, calculating grouped means:

existing code: prints an error.

grouped_data.mean()

Updated code: explicitly specify to calculate grouped means for numerical columns only.

grouped_data.mean(numeric_only = True)

[nkandhari]

The same changes must be made in the half-day and the full-day workshops.