chore: bump the actions group across 1 directory with 2 updates

Bumps the actions group with 2 updates in the / directory: [actions/download-artifact](https://github.com/actions/download-artifact) and [actions/setup-node](https://github.com/actions/setup-node).


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

Updates `actions/setup-node` from 5 to 6
- [Release notes](https://github.com/actions/setup-node/releases)
- [Commits](actions/setup-node@v5...v6)

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

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

Author: dependabot[bot]

.github/workflows/cd.yml

@@ -43,7 +43,7 @@ jobs:
     if: github.event_name == 'release' && github.event.action == 'published'
 
     steps:
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           name: Packages
           path: dist

.github/workflows/validate-zenodo.yml

@@ -8,7 +8,7 @@ jobs:
 
     steps:
       - uses: actions/checkout@v5
-      - uses: actions/setup-node@v5
+      - uses: actions/setup-node@v6
         with:
           node-version: "22"
       - name: Install dependencies