Take a Look the the Left.
Theres a Huge List of Builds. If you click on the Last one: "#177"
It goes to that Build, check what is mentioned there:
Update to Spigot-1.12-pre5
(detail / githubweb)
That means, you have to grab a build a bit older.
Maybe try #176 or #174
also, to make sure you understand the page:
#175 is no good. That Build Failed, it probably wont work. (Thats why its marked with a Red Dot)