add crs when writing DriverVectorCube to geojson file

Author: JeroenVerstraelen

openeo_driver/datacube.py

@@ -573,7 +573,7 @@ def write_assets(
             return self.to_legacy_save_result().write_assets(directory)
 
         gdf = self._as_geopandas_df(flatten_prefix=options.get("flatten_prefix"))
-        gdf.to_file(path, driver=format_info.fiona_driver)
+        gdf.to_file(path, driver=format_info.fiona_driver, crs=self.get_crs())
 
         if not format_info.multi_file:
             # single file format