Bump dawidd6/action-download-artifact from 20 to 21

Bumps [dawidd6/action-download-artifact](https://github.com/dawidd6/action-download-artifact) from 20 to 21.
- [Release notes](https://github.com/dawidd6/action-download-artifact/releases)
- [Commits](dawidd6/action-download-artifact@v20...v21)

---
updated-dependencies:
- dependency-name: dawidd6/action-download-artifact
  dependency-version: '21'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]

.github/workflows/submit_coverage.yml

@@ -16,7 +16,7 @@ jobs:
     if: github.event.workflow_run.conclusion == 'success'
     steps:
       - name: Download artifact
-        uses: dawidd6/action-download-artifact@v20
+        uses: dawidd6/action-download-artifact@v21
         with:
           workflow: ${{ github.event.workflow_run.workflow_id }}
           workflow_conclusion: success