Configure auto-merge for patch / pin update types

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](https://docs.renovatebot.com/key-concepts/automerge/#automerge-non-major-updates) a reference implementation.
- 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.

まずリポジトリの Renovate 設定を見つけ、リンクされている Renovate の automerge ガイダンスを確認します。次に、Renovate が pull request をマージするために必要なリポジトリ設定を調べます。patch、pin、digest の更新が automerge 用に設定され、1.0.0 未満の依存関係と必須チェックが記載された考慮事項に従っていれば完了です。

索引モデルが issue の本文から書いたものです。