simpletuner 4.2.0 crashes on import: skrample.common has no attribute 'SigmaTransform'

simpletuner 4.2.0 + skrample 0.6.0 (latest on PyPI) `simpletuner server` crashes on startup: ``` Error starting server: module 'skrample.common' has no attribute 'SigmaTransform' simpletuner/helpers/scheduled_sampling/skrample_adapter.py", line 8, in <module> def make_sigma_schedule_from_ddpm(noise_schedule) -> tuple[np.ndarray, sk_common.SigmaTransform]: ^^^^^^^^^^^^^^^^^^^^^^^^ AttributeError: module 'skrample.common' has no attribute 'SigmaTransform' ``` skrample 0.6.0 doesn't expose `SigmaTransform` or `sigma_polar` in `skrample.common`. one workaround is adding `from __future__ import annotations` to skrample_adapter.py to defer the type annotation evaluation.