Faster tests

[tgrandje]

#299 and #296

[tgrandje]

In the present state, that PR should'nt be merged until we state on #303 : it uses a recent geopandas functionality which is not available in the latest py3.9-compatible geopandas release.

[tgrandje]

OK, this is good for review.

I dumped most of the tree decision managing department's retrieval as it was not easy to maintain and could somehow be quite slow. It's been simplified to 3 cases:

• either we're working on the department's dataset (same as before)
• or we're on a dataset where INSEE (now) displays insee dpt codes (that's the case for EPCIs for instance) ;
• or in any other case, it's fast enough to use a sjoin (assuming we already stored a preprocessed departments' geodataset).

During my manual tests, I've mostly seen awkward results for "collectivités territoriales" (Saint-Martin, Saint-Barthélémy) or some other exotic cases : for instance arrondissements municipaux datasets, cantons, where there are holes in french territory or when you choose to zoom in on Paris' inner suburbs and your current dataset has geometries maching Paris's external suburbs. I don't think that was ever perfectly rendered in pynsee...