Totalsegmentator

* add brain structures
* add liver vessels
* greatly improved phase classification model

* Bugfixes
* add headneck structures

* also return statistics from python api
* add `totalseg_get_phase`
* major bugfix: rib labels were in wrong order
* hide nnunetv2 2.3.1 warning: `Detected old nnU-Net plans format. Attempting to reconstruct network architecture...`
* add mr models

* Bugfix: add flush to DummyFile
* Require python >= 3.9 in setup.py
* properly add `vertebrae_body` model
* add `--roi_subset_robust` argument
* add `--fastest` argument
* allow `mps` as device (but not supported by pytorch yet)
* add inline python version requirement for `requests` package
* if input spacing same as resampling spacing then skip resampling
* from python api also return nifti with label map in header
* input to python api can be a Nifti1Image object or a file path
* upgrade to `nnunetv2>=2.2.1`
* for `total` task use nnU-Net `step_size=0.8` instead of `0.5` for faster runtime while only decreasing dice by 0.001
* minor edits and bugfixes

* downgrade nnunet to 2.1 to fix bug in `fast` model

* temporary fix of critical bug in `fast` model. Proper fix in next release.