support tuple in addition to list in geojson dict
The geojson output of rasterio.features.shapes (https://rasterio.readthedocs.io/en/latest/api/rasterio.features.html#rasterio.features.shapes) looks like this:
{'type': 'Polygon', 'coordinates': [[(18.0, 0.0), (18.0, 1.0), ...With the coordinates represented as tuples. This fix will add support for this format.