Copier safe template has arbitrary filesystem read access via symlinks when _preserve_symlinks: false

Copier is a library and CLI app for rendering project templates. Prior to version 9.11.2, Copier suggests that it's safe to generate a project from a safe template, i.e. one that doesn't use unsafe features like custom Jinja extensions which would require passing the `--UNSAFE,--trust` flag. As it turns out, a safe template can currently include arbitrary files/directories outside the local template clone location by using symlinks along with `_preserve_symlinks: false` (which is Copier's default setting). Version 9.11.2 patches the issue.