chore(deps): update actions/upload-artifact action to v4 (#25)

Author: renovate[bot]

.github/workflows/python.yml

@@ -37,7 +37,7 @@ jobs:
     - uses: NiklasRosenstein/slap@gha/install/v1
     - run: slap install --only-extras docs --no-venv-check
     - run: slap run --no-venv-check docs:build
-    - uses: actions/upload-artifact@v2
+    - uses: actions/upload-artifact@v4
       with:
         name: docs
         path: docs/_site