Bump the github-actions group

Bumps the github-actions group in /.github/workflows/unstash with 1 update: [actions/download-artifact](https://github.com/actions/download-artifact).

- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v3...v4)

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

Signed-off-by: dependabot[bot] <[email protected]>

.github/workflows/unstash/action.yml

@@ -13,7 +13,7 @@ runs:
   using: "composite"
   steps:
     - name: Download stash
-      uses: actions/download-artifact@v3
+      uses: actions/download-artifact@v4
       with:
         name: ${{ inputs.name }}
         path: ${{ runner.temp }}