chore: allow sphinx-autobuild to choose port for serving docs (#3959)

Makefile

@@ -136,7 +136,7 @@ docs-clean: 										## Dump the existing built docs
 
 docs-serve: docs-clean 								## Serve the docs locally
 	@echo "=> Serving documentation"
-	uv run --python 3.12 sphinx-autobuild docs docs/_build/ -j auto --watch litestar --watch docs --watch tests --watch CONTRIBUTING.rst --open-browser
+	uv run --python 3.12 sphinx-autobuild docs docs/_build/ -j auto --watch litestar --watch docs --watch tests --watch CONTRIBUTING.rst --open-browser --port=0
 
 docs: docs-clean 									## Dump the existing built docs and rebuild them
 	@echo "=> Building documentation"