Lots of projects now use tools.deps with the Clojure CLI.

Personally, I haven't used leiningen in over a year and avoid uberjar whereever I can (and I very well can with tools.deps!)

If a project has a deps.edn it can be run directly (no uberjars needed):
clj -m my-project.main

This is a much simpler, lightweight and flexible approach. It would be awesome if heroku supported it, especially given that it looks like the Clojure CLI is already installed by this buildpack.