Bump dawidd6/action-download-artifact action to v21

Author: renovate[bot]

.github/workflows/quality-monitor-build.yml

@@ -26,7 +26,7 @@ jobs:
         with:
           maven-version: 3.9.14
       - name: Download reference reports from main branch
-        uses: dawidd6/action-download-artifact@v6
+        uses: dawidd6/action-download-artifact@v21
         with:
           workflow: quality-monitor-build.yml
           branch: main