Raster astype() converts the nodata by default even if type is the same

[rhugonnet]

We previously discussed having a convert_nodata option to Raster.astype() to ensure nodata is supported, and avoid problems when writing etc..., which is now the default:

geoutils/geoutils/raster/raster.py

Line 1444 in 1594501

def astype(

However, if the type is the same, astype will still update the nodata value, which is not intuitive (made me look for a bug in tests for an 1h when running raster_equal(). Should we skip convert_nodata in the case where astype() is the same as the existing type, and (potentially) raise a warning?