Fix SBNoiseScheduleVE.g() time handling

[fallintoplace]

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What does this PR do ?

Fix SBNoiseScheduleVE.g() so it uses the provided time argument instead of a nonexistent self.time, and keep the scalar diffusion coefficient on the same dtype/device as the input tensor.

Collection: Audio

Changelog

• replace the invalid self.time reference in SBNoiseScheduleVE.g() with the method argument time
• convert c to a tensor on time's dtype/device before taking the square root
• add a regression test that checks the numerical result and dtype/device preservation

Usage

g = noise_schedule.g(time)

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Additional Information

• Related to #
• I couldn't run pytest in this checkout because the active interpreter is missing pytest, and it is also missing torch, so I verified the change with python3 -m compileall, git diff --check, and an isolated smoke test that executes the patched method body with lightweight stubs.

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