vtkVoxel support in vtu files

[soerenPeters]

Hi, while working with meshio, we noticed that vtkVoxel in particular is not supported:
https://github.com/nschloe/meshio/blob/main/src/meshio/_vtk_common.py

My question is whether there were special reasons for this, or whether it makes sense to add this feature ourselves.

Thanks in advance for your answers.