This is currently limited by vtk not supporting Python 3.13. Here is the issue tracking this: https://gitlab.kitware.com/vtk/vtk/-/issues/19489

It looks like VTK now ships 3.13. @pshriwise or @paulromano, could you trigger GHA to rerun?

Still failing as there are no Python 3.13 wheels on PyPI

My bad. I misinterpreted what had happened in the VTK repo.

Update. VTK is being held back by mpi4py. mipy4py 4.x does support 3.13, but they are pinned to version 3.x, which has no plans to support 3.13. So until they are able to migrate to the next release of mpi4py, which will be non-trivial, this upgrade is blocked.

The changes have been made, but are not currently planned to be incorporated into the next release yet.

@paulromano or @pshriwise. I think this is ready for review. It's not showing as completed as a lot of the required jobs are for python 3.10 which technically shouldn't be supported anymore. I'd suggest moving these to python 3.11 or 3.13.

Just noticed this conda forge PR that was automatically created. Perhaps of interest as it attempts to build the conda package for 3.13
conda-forge/openmc-feedstock#75

Quickly looking into that it looks like Conda is search for a release candidate for Py 3.13 and Numpy 2.x. I'm not sure exactly why it's doing that, but this would be for 0.15.0 that it is attempting. I'm thinking of just letting that fail and add py 3.13 to the next release.

Thanks @paulromano!