dependabot: add "github-actions"

[HuijingHei]

Inspired by coreos/bootupd#758 (comment)

[travier]

We should probably add it to https://github.com/coreos/repo-templates/blob/main/dependabot/dependabot.yml as well so that it's propagated to all our repos

[HuijingHei]

We should probably add it to https://github.com/coreos/repo-templates/blob/main/dependabot/dependabot.yml as well so that it's propagated to all our repos

Not sure if my understanding is correct, add it to dependabot.yml, and curious how this works, do you have related docs?

[travier]

We have github actions in all repos so we can probably make that a static addition in this file and not a conditional one.

[travier]

i.e. we would directly include:

  - package-ecosystem: "github-actions"
    directory: "/"
    schedule:
      interval: "weekly"
    open-pull-requests-limit: 3

right at the top of this list here

[travier]

I'm afraid that the only doc about how this repo works is in the README: https://github.com/coreos/repo-templates#coreos-repo-templates

The short version is that this generates the files from the templates and creates PRs to the repos to sync them.