📝 Update installation of freethreaded Python

Author: veit

docs/install.rst

@@ -77,7 +77,7 @@ If different Python versions are required, for example to test libraries with
 :doc:`test/tox`, I use `uv <https://docs.astral.sh/uv/guides/install-python/>`_.
 This allows not only older CPython versions to be installed but also  `PyPy
 <https://pypy.org>`_ or free-threaded Python 3.13 with ``uv python install
-[email protected]`` or ``uv python install 3.13t``.
+[email protected]`` or ``uv python install --python-preference only-managed 3.13t``.
 
 .. tip::
    `direnv <https://direnv.net>`_ allows you to set environment variables