Automatic rebase for dependabot PRs on changes to the target branch

[mfranzke]

In case of any changes to the target branch we might need to tell dependabot to rebase it's pull request. With a huger amount of PRs, this might get a time consuming task, so we should look into this whether we could automate this task.

Candidates:

• https://github.com/marketplace/actions/gha-auto-dependabot-rebase
• kodiak: https://kodiakhq.com/docs/config-reference#mergeautomerge_dependenciesversions (might be the better option as it would update all PRs, not just dependabot)
  • example: https://github.com/Maxim-Mazurok/google-api-typings-generator/blob/40d393bdb1e41d72599250c5366c1e83b8eac5ce/.kodiak.toml