Fixing the Toiletpaper.calculate_price to match Fruit.calculate_price

[hjoaquim]

Ultra small PR to address this ^
Also because having it return price_per_unit doesn't really make sense in an object that has the nr_units attribute.

[majkah0]

Hi @hjoaquim, thank you for pointing this out. We are usually preparing the materials in another, private repo, so fixing it here will not make the change permanent. Could you please open an issue about it here? Describe the issue and suggest a solution. Thank you very much!