CI: 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](https://github.com/dawidd6/action-download-artifact/compare/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>

.github/workflows/js-and-wasm-benchmarks.yml

@@ -53,7 +53,7 @@ jobs:
           sudo apt-get install -y python3-venv
 
       - name: 'Download JS repl artifact'
-        uses: dawidd6/action-download-artifact@v20
+        uses: dawidd6/action-download-artifact@v21
         with:
           run_id: ${{ github.event.workflow_run.id }}
           name: ladybird-js-${{ matrix.package_type }}
@@ -73,7 +73,7 @@ jobs:
           echo "sha=${commit_hash}" >> "${GITHUB_OUTPUT}"
 
       - name: 'Download wasm repl artifact'
-        uses: dawidd6/action-download-artifact@v20
+        uses: dawidd6/action-download-artifact@v21
         with:
           run_id: ${{ github.event.workflow_run.id }}
           name: ladybird-wasm-${{ matrix.package_type }}