chore(deps): bump torch in /backend/python/vllm

Bumps torch from 2.9.1+cpu to 2.12.1+xpu.

---
updated-dependencies:
- dependency-name: torch
  dependency-version: 2.12.1+xpu
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

backend/python/vllm/requirements-cpu.txt

@@ -1,6 +1,6 @@
 --extra-index-url https://download.pytorch.org/whl/cpu
 accelerate
-torch==2.9.1+cpu
+torch==2.12.1+xpu
 torchvision
 torchaudio
 transformers