fix artifact name

Author: 2bndy5

.github/workflows/perf-test.yml

@@ -122,6 +122,7 @@ jobs:
       - name: Upload JSON results
         uses: actions/upload-artifact@v4
         with:
+          name: benchmark-json
           path: ${{ runner.temp }}/benchmark.json
       - name: Annotate summary
         run: python .github/workflows/perf_annotate.py "${{ runner.temp }}/benchmark.json"