Bump actions/download-artifact from 5 to 6

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 5 to 6.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v5...v6)

---
updated-dependencies:
- dependency-name: actions/download-artifact
  dependency-version: '6'
  dependency-type: direct:production
  update-type: version-update:semver-major
...

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

Author: dependabot[bot]

.github/workflows/test_action.yaml

@@ -26,7 +26,7 @@ jobs:
           printf "Removing generated files...\n"
           rm -f chart.md schedule.json schedule.md
           ls -R
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: spec-zero-versions
       - name: Display structure of downloaded files