chore(deps): Bump torchvision from 0.18.1+rocm6.0 to 0.20.0+cu118 in /backend/python/diffusers (#3997)

chore(deps): Bump torchvision in /backend/python/diffusers

Bumps torchvision from 0.18.1+rocm6.0 to 0.20.0+cu118.

---
updated-dependencies:
- dependency-name: torchvision
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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