Bump actions/download-artifact from 5 to 6 (#3787)

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

- vLLM version: v0.11.0rc3
- vLLM main:
c9461e05a4

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

.github/workflows/vllm_ascend_test_models.yaml

@@ -116,7 +116,7 @@ jobs:
           git checkout -B "${BRANCH_NAME}" upstream/main
 
       - name: Download only current run reports
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           path: ./docs/source/developer_guide/evaluation/accuracy_report
           pattern: report-*