This has been added for MM:S now.
For both MM:S and SM, please don't rely on the directory listing being available, let alone scraping it. This is the preferred method, using the "latest.php". It exists on both metamodsource.net and sourcemod.net, and takes two GET params, os and version.
os can be windows, linux, or mac
version is the branch base version, such as 1.8, 1.9, 1.10, etc.
https://www.metamodsource.net/latest...x&version=1.10