Silence warning from `tar_terra_sprc()`

[Aariq]

Using tar_terra_sprc() results in the warning [rast] skipped sub-datasets (see 'describe(sds=TRUE)'). I'm fairly certain this is because terra::writeRaster() returns a SpatRaster object (rather than a file path, which is what I'd expect) and it only returns the first file in the sprc when other rasters are added with APPEND_SUBDATASET=YES. Unless there is a way to change the behavior of writeRaster() to not return the result of rast(), it might be better to just silence this warning in the write function of tar_terra_sprc()