[python] Make bindings work with dune 2.9
This is a second attempt at !2912 (closed) to make Python work with dune 2.8 and dune 2.9. The two versions feature incompatible ways of setting up the Python bindings.
This is a second attempt at !2912 (closed) to make Python work with dune 2.8 and dune 2.9. The two versions feature incompatible ways of setting up the Python bindings.