Bump actions/download-artifact from 2 to 4

Bumps [actions/download-artifact](https://github.com/actions/download-artifact) from 2 to 4.
- [Release notes](https://github.com/actions/download-artifact/releases)
- [Commits](actions/download-artifact@v2...v4)

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

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

.github/workflows/pythonpublish.yml

@@ -48,7 +48,7 @@ jobs:
           python -m pip install --upgrade pip
           pip install twine
       - name: Download wheels
-        uses: actions/download-artifact@v2
+        uses: actions/download-artifact@v4
       - name: Publish wheels
         env:
           TWINE_USERNAME: ${{ secrets.PYPI_USERNAME }}