Thank you for suggestion and sorry for the inconvenience. You're right that would be great to implement such a feature.
Unfortunately, on all other OS, we're still supporting all previous versions including Windows XP, but Apple continuously forcing us to upgrade our build machines and eliminate support of old versions of OSX.
Although we would love to support old versions, there were some critical fixes (security and stability) which were released only for the newest XCode environment. Unfortunately, this meant to cut old OSX versions.
Anyway, previous versions can be found here: https://www.skipper18.com/en/download/previous-releases