Implement `Affine.from_shapely` classmethod

[kopytjuk]

Hey guys, first of all, thanks for the library, it is really well documented and has a nice API!

I often work with rasterio (where affine.Affine) is heavily used and also with shapely - since we have a to_shapely() method, would it make sense to implement a from_shapely() constructor? Ofc, I can contribute, it just makes the interoperability between two libarary families easier.

I am aware that it is just a very simple function, but it just avoids the mental hassle with writing the indices

def transform_shapely_order_to_affine(shapely_transform: tuple[float]) -> Affine:

    # shapely (a,b,d,e,xoff,yoff) order
    return Affine(shapely_transform[0], shapely_transform[1], shapely_transform[4], shapely_transform[2], shapely_transform[3], shapely_transform[5])

What do you think?