Cpu-based inference

[akhanf]

Thanks to @ylugithub there is a nnunet fork that works on CPU or GPU for inference. This PR updates the dependencies to use that fork (will replace this with a future release of nnunet once it becomes integrated), and adds a couple cmd-line options for enabling gpu (--use_gpu, which sets the resources for the run_inference rule), and a --nnunet_disable_tta to disable test-time augmentation.

By default use_gpu is set to false, although this really only makes a difference to snakemake profiles that use the gpus resource (e.g. cc-slurm).. maybe could change it to --request_gpu_resources to be clear that it is not enabling/disabling GPU more generally..