CI job for submitting dependency graph to GitHub

[armanbilge]

So this is a really cool idea: https://github.com/ckipp01/mill-github-dependency-graph

It uses new GitHub API described here:
https://github.blog/2022-06-17-creating-comprehensive-dependency-graph-build-time-detection/

Basically it would be a way to get our dependencies registered on this page:
https://github.com/typelevel/sbt-typelevel/network/dependencies

This is beneficial for security/vulnerability alerts. And maybe we can also get one of those cool "used by n" widgets on our repos 😂

I don't think an sbt version of that plugin should live here, but when it exists, I think we should integrate with it.

[armanbilge]

Ah, seems there may be an official announcement soon :)
https://github.com/scalacenter/sbt-dependency-graph-action