Raster.set_ndv does not work with multiple nodata values

[adehecq]

Describe the bug
Raster.set_ndv supposedly accept several nodata values, but this hasn't been tested and it fails.
Related to #223 .

To Reproduce

import geoutils as gu
img = gu.Raster(gu.datasets.get_path("landsat_RGB"))
img.set_ndv([2,3, 4])

fails with error

ValueError: Given nodata value, [2, 3, 4], is beyond the valid range of its data type, uint8.

Expected behavior
This should not raise an error.
Apparently, this is not possible to create a raster with several nodata values at the moment with rasterio. This has been raised as an issue: rasterio/rasterio#2234
In the meantime, a quick fix would be to add a NotImplementedError if several nodata values are passed.

System (please complete the following information):
irrelevant

Additional context
None