chore(deps): bump grpcio from 1.81.1 to 1.82.1 in /backend/python/vllm (#10808)

Bumps [grpcio](https://github.com/grpc/grpc) from 1.81.1 to 1.82.1.
- [Release notes](https://github.com/grpc/grpc/releases)
- [Commits](https://github.com/grpc/grpc/compare/v1.81.1...v1.82.1)

---
updated-dependencies:
- dependency-name: grpcio
  dependency-version: 1.82.1
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

Signed-off-by: dependabot[bot] <support@github.com>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

backend/python/vllm/requirements.txt

@@ -1,4 +1,4 @@
-grpcio==1.81.1
+grpcio==1.82.1
 protobuf
 certifi
 setuptools