Make focal work on 3d-arrays

[sebiegli]

I'd like to use the focal-functionalities of xarray-spatial to calculate some statistics for a raster with multiple bands (in my case R, G and B). Unfortunately, so far, focal seems to be limited to 2d-arrays, eg. when handing over a RGB-3d-array to focal.apply() I get this error message:

ValueError: raster must be 2D

Is there a way of calculating focal statistics on multiple bands? Or are there plans to include this functionality in the future?

[brendancol]

@sebiegli sorry for the delayed response. The was just merged in #924