Fetch stores taxonomies

[raphodn]

Story

In taxonomy.py it's currently not possible to fetch the (currently unused) stores taxonomies.

Would it be possible to allow this? I can open a PR :)

Linked with:

• Taxonomize stores - Add autosuggest for stores openfoodfacts-server#7632 (comment)
• Location: match OSM brand with a logo open-prices#1148