remove shapely

[vincentsarago]

Note: This could be considered as a breaking change

I've noticed that Polygon was imported twice:

• from geojson_pydantic
• from shapely.geometry

Because the one from shapely was imported later, it was the one used in the GeoJson type:

openeo-pg-parser-networkx/openeo_pg_parser_networkx/pg_schema.py

Line 349 in 9f72a9d

GeoJson = Union[FeatureCollection, Feature, GeometryCollection, MultiPolygon, Polygon]

resulting in the type being an Union of pydantic model and Shapely object

I personally think that using shapely only for the polygon object is kinda overkill, but if users really need it, it might better be in a BoundingBox.to_shapely() method