Compatibility with rasterio 1.4.0

[martinfleis]

Some dtype changes in rasterio 1.4.0 broke zonal stats in certain occasions - see https://github.com/martinfleis/sds/actions/runs/11103109876/job/30844359444

[coolzhao]

Hi @martinfleis, I encountered the same problem when doing zonal statistics for a binary DataArray. I found the problem is already solved in the source code by specifying the dtype as float32 since the rasterize function tries to fill np.nan for all areas not covered by input geometries.

I suggest that instead of forcing a float32 dtype, it's better to check the input raster data type first. If the input data type is float64 or float32, the output should use the original data type. If integer, then the output can use float32.

Also, I think it's better to set fill and dtype as two input parameters for the _zonal_stats_rasterize function so that the user can be aware of that and may change it as needed for memory efficiency. Cheers.

[martinfleis]

@coolzhao Could you turn these suggestions in a PR? I am aware this is suboptimal.

[coolzhao]

@martinfleis Yes, I would be happy to help on this and will try to do a PR later.