Issue #354: avoid numpy arrays from DriverVectorCube.to_internal_json

Note that `DataArray.to_dict()` only supports `data="list"` from
xarray>=2023.05. In python 3.8 environments (still default at moment),
highest xarray version is 2023.01, where `data` argument is expected to
be bool. However, in those situations `data="list"` will be interpreted
as True, which is actually fine.
So this fix is backward compatible (somewhat accidentally)

Author: soxofaan

openeo_driver/datacube.py

@@ -556,7 +556,7 @@ def to_internal_json(self) -> dict:
         """
         return {
             "geometries": shapely.geometry.mapping(self._geometries),
-            "cube": self._cube.to_dict(data="array") if self._cube is not None else None,
+            "cube": self._cube.to_dict(data="list") if self._cube is not None else None,
         }
 
     def get_crs(self) -> CRS: