Challenge 'Refactoring To Use a Pure Function' does not use solution implementation from previous challenge

In episode 3.4 we introduce a class-based solution for loading in csv files in `analyse_data()`: https://carpentries-incubator.github.io/python-intermediate-development/33-code-decoupling-abstractions/index.html#solution-1

In the later solution we still use the old implementation, whereas students at that point will have the class-based implementation of analyse_date() https://carpentries-incubator.github.io/python-intermediate-development/34-code-refactoring/index.html#exercise-refactoring-to-use-a-pure-function