Sphinx 8.2 changed the definition of `depart_admonition`, causing build failures when building with html-docs=enabled as mesa was only overloading `visit_admonition`. This adds the old `depart_admonition` definition to mesa's copy, restoring compatibility and fixing the build. Closes: https://gitlab.freedesktop.org/mesa/mesa/-/issues/12725 Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/34165>