Enable a `latest` symlink on the ftp index

Hello all 👋
I recently talked with a friend of mine (@sdelquin) and he has a specific use-case for the ftp directory on his Python seminars and usually the students are requested to download "the latest Python version" from the command-line, from which he developed a little ad-hoc script to get such function:

PYTHON_LATEST=`curl -s https://www.python.org/downloads/ | gunzip -c | grep latest | perl -nle 'print $1 if /(\d+\.\d+\.\d+)/'`
PYTHON_DOWNLOAD=https://www.python.org/ftp/python/$PYTHON_LATEST/Python-$PYTHON_LATEST.tgz

This use-case could be improved if we have a latest symlink at https://www.python.org/ftp/python/ always pointing to the latest stable release.

I'm not certain how to implement this, because I'm not aware of how the ftp index is generated, but I have the feeling it shouldn't be so complicated, considering that during the release process, the release managers can select a checkbox to say "this is the latest release".

In my experience this is nothing new, and in some other indexes it's common to find a latest symlink, like this example

Just for the record, I already talked about this with @hugovk and @ewdurbin but I'm opening an issue so the discussion can stay in one place :)

Commencez par retracer comment l’index FTP est généré et comment le processus de release enregistre la release stable la plus récente ; la description ne nomme aucun fichier ni test précis. Le travail est considéré comme terminé lorsque l’index FTP Python expose un lien symbolique latest qui pointe vers la release stable la plus récente et reste correct après les releases.