Automatically detect when an imported project gets bumped upstream, and use its version. Idea from [#Palomar > Suggested additions to the "About" page @ 💬](https://leanprover.zulipchat.com/#narrow/channel/621638-Palomar/topic/Suggested.20additions.20to.20the.20.22About.22.20page/near/618170601)
Automatically detect when an imported project gets bumped upstream, and use its version.
Idea from #Palomar > Suggested additions to the "About" page @ 💬