chore(deps): update actions/download-artifact action to v4 (#23)

Author: renovate[bot]

.github/workflows/python.yml

@@ -47,7 +47,7 @@ jobs:
     runs-on: ubuntu-latest
     steps:
     - uses: actions/checkout@v2
-    - uses: actions/download-artifact@v2
+    - uses: actions/download-artifact@v4
       with: { name: docs, path: docs/_site }
     - uses: JamesIves/[email protected]
       with: { branch: gh-pages, folder: docs/_site, ssh-key: "${{ secrets.DEPLOY_KEY }}" }