Consider adding dependabot for golang, nodejs, and github actions

[josegonzalez]

While dependabot can sometimes be a bit noisy, it forces you to consider upgrading dependencies as they update upstream, ensuring you never get into a state where upgrading is a pain because its not just one dependency.

Here is the one for the Dokku project, which has a variety of examples for usage. I'd be happy to PR a config for you if you think this would be a good idea.