refactor(datasets) Update type hinting generics based on typing module

[adam-narozniak]

Issue

Flower datasets in 2 files still uses the Type Hinting Generics from typing module == from typing import List, Tuple

Proposal

Update (as suggested by the formatter) the Type Hinting Generics from typing module to directly using standard collections (dict, list, ...)

Explanation

As PEP 585 suggests from python 3.9 the latter is possible seamlessly + the automatic change happens when using the formatting script.