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

Author: renovate[bot]

.github/workflows/deploy-docs.yml

@@ -51,7 +51,7 @@ jobs:
         uv run sphinx-build -b html docs/source build/html
 
     - name: Upload artifact
-      uses: actions/upload-pages-artifact@v3
+      uses: actions/upload-pages-artifact@v4
       with:
         path: build/html