Configure auto-merge for patch / pinning updates

Add renovate config to auto-merge any `patch`, `pin` or `digest` update types.

Some considerations:

- [Changes](https://docs.renovatebot.com/key-concepts/automerge/#if-you-dont-use-github-actions) would be required to the repository settings to enable renovate to auto-merge it's PRs.
- There are [workarounds for required PR reviews](https://docs.renovatebot.com/key-concepts/automerge/#required-pull-request-reviews).
- We'd probably want to exclude any pre 1.0.0 dependency as they can make breaking changes at any time. Here's an example to [implement this](https://docs.renovatebot.com/key-concepts/automerge/#automerge-non-major-updates).
- Finally, the way github handles [skipped but required checks seems a bit weird](https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/collaborating-on-repositories-with-code-quality-features/troubleshooting-required-status-checks#handling-skipped-but-required-checks) and unless all checks pass, renovate wouldn't be able to auto-merge. They should've taken [this](https://github.com/orgs/community/discussions/13690#discussioncomment-2641965) suggestion lol.