chore(deps): update actions/download-artifact action to v6 (#3501)

Co-authored-by: Renovate Bot <[email protected]>

Author: thomhurst

.github/workflows/speed-comparison.yml

@@ -68,7 +68,7 @@ jobs:
           dotnet-version: 10.0.x
 
       - name: Download Build Artifacts
-        uses: actions/download-artifact@v5
+        uses: actions/download-artifact@v6
         with:
           name: test-builds-${{ matrix.os }}
           path: tools/speed-comparison/UnifiedTests/bin/