open3d limiting python ver < 3.12

[michaelmckinsey1]

https://pypi.org/project/open3d says it should support python 3.12, but if you try to install it with 3.12 you should get an error that no matching distribution found (or at least last time I tried). Even still, we should be able to run with 3.13 and 3.14. So do we need an alternative to open3d?

[PatrickRMiles]

How fun. We probably should try to remove the o3d dependency. I'll look into it.

[PatrickRMiles]

Looking at our use of Open3D, we basically:

1. generate an instance point cloud in a numpy array
2. convert the numpy array to an o3d point cloud and save that
3. read the o3d point cloud in volumegen
4. convert that into a numpy array...........
5. continue with volumegen

I'm pretty sure the o3d use is a relic from the original work + codebase that inspired this project, so this must have just been carried forward since then. I'll get a branch up that removes this.