Deploying an non standard app structure (dave thomas tutorial) to heroku

I’m trying to deploy an elixir app to heroku that was build using a project structure following @pragdave 's excellent tutorials. Here is an example of such a structure:

Basically the web directory is the main entry point and the other directories are just related libraries.
I’m trying to deploy this to heroku but the heroku build packs don’t recognise my project as a valid app and I can’t figure out how to either modify my project or modify the build pack to get it to work.

Does anyone know how?