📦 Add Dependabot file

[tomrijnbeek]

✨ What's this?

Adds a Dependabot config file for this repository.

🔍 Why do we want this?

This will automatically keep dependencies up-to-date. This is something we do across all the other bearded libraries as well.

🏗 How is it done?

Ctrl+C; Ctrl+V

Usually I put my name as "assignee" on these configs, but I wasn't sure how you feel about that for this library.