🛠️ Bump actions/download-artifact from 4 to 6

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 4 to 6.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v4...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] <[email protected]>

Author: dependabot[bot]

.github/workflows/deploy.yml

@@ -117,7 +117,7 @@ jobs:
 
     # TODO (peterdavidfagan): don't hardcode branches for downloads
     - name: Download Rolling Artifacts
-      uses: actions/download-artifact@v4
+      uses: actions/download-artifact@v6
       with:
         name: main_html_artifacts
         path: .
@@ -129,7 +129,7 @@ jobs:
         rm artifact.tar.gz
 
     - name: Download Humble Artifacts
-      uses: actions/download-artifact@v4
+      uses: actions/download-artifact@v6
       with:
         name: humble_html_artifacts
         path: .