Automatically Merge Dependabot's Pull Requests

[vorburger]

• https://docs.github.com/en/code-security/dependabot/working-with-dependabot/automating-dependabot-with-github-actions
• https://stackoverflow.com/questions/64116781/how-do-i-automerge-dependabot-updates-config-version-2
• https://dev.to/slashgear_/how-to-automatically-merge-dependabot-pull-requests-with-github-actions--30pe
• https://blog.somewhatabstract.com/2021/10/11/setting-up-dependabot-with-github-actions-to-approve-and-merge/

This is NOT the same as https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/incorporating-changes-from-a-pull-request/automatically-merging-a-pull-request - it took me a minute to understand the difference: What that allows you to do is manually signaling "I'm OK for this PR to be automatically merged by GH once it builds", but still with a human's review & click. What this would do is fully automatically merge PRs from (only) dependabot if they build.

@edewit FYI