Update dawidd6/action-download-artifact action to v21 (#340)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

.github/workflows/process-test-results.yml

@@ -26,7 +26,7 @@ jobs:
 
     steps:
       - name: Download and Extract Artifacts
-        uses: dawidd6/action-download-artifact@v20
+        uses: dawidd6/action-download-artifact@v21
         with:
           run_id: ${{ github.event.workflow_run.id }}
           path: artifacts