Switch from segmentation_models_pytorch to torchseg

[Pale-Blue-Dot-97]

It appears that segmentation_models_pytorch is no longer maintained. minerva uses it for providing a library of segmentation models for testing and experiments. However, it is pinned to a now quite old timm==0.9.2 which is now causing conflicts with other dependencies.

The solution it seems is to switched to an actively maintained fork of segmentation_models_pytorch called torchseg