DEV: Bump actions/download-artifact from 5 to 6 (#3505)

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] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>

Author: dependabot[bot]

.github/workflows/github-ci.yaml

@@ -230,7 +230,7 @@ jobs:
 
       - run: python -m pip install --upgrade coverage[toml]
 
-      - uses: actions/download-artifact@v5
+      - uses: actions/download-artifact@v6
         with:
           pattern: coverage-data*
           merge-multiple: true

.github/workflows/publish-to-pypi.yaml

@@ -44,7 +44,7 @@ jobs:
 
     steps:
     - name: Download all the dists
-      uses: actions/download-artifact@v5
+      uses: actions/download-artifact@v6
       with:
         name: python-package-distributions
         path: dist/