Bump actions/upload-artifact from 5 to 6 (#5014)

Bumps
[actions/upload-artifact](https://github.com/actions/upload-artifact) from 5 to 6.

- vLLM version: v0.12.0
- vLLM main:
ad32e3e19c

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

.github/workflows/schedule_test_benchmarks.yaml

@@ -134,7 +134,7 @@ jobs:
 
       - name: Upload benchmark artifacts
         if: github.event_name != 'schedule' && github.event_name != 'workflow_dispatch'
-        uses: actions/upload-artifact@v5
+        uses: actions/upload-artifact@v6
         with:
           name: "benchmark-performance-${{ matrix.vllm_branch }}-${{ matrix.vllm_ascend_branch }}-report"
           path: ./benchmarks/results/benchmark_results.md