release upon dependency changes from renovate-bot

The `release-please` README [says](https://github.com/googleapis/release-please) that it will only create a release if there are "releaseable units", i.e. commits with one of the following prefixes: `feat`, `fix`, or `deps`. It specifically states `A "chore" or "build" commit is not a releasable unit.`

The commits generated by renovate-bot are prefixed by `chore(deps)`, so **they are excluded from the release criteria**. However, it seems that the intent of release-please is to re-release when there are dependency changes, correct?

In that case, it seems release-please should be made to accommodate renovate-bot commit messages.

If we explicitly want to exclude renovate-bot changes from triggering release-please (eg because of their frequency?), let's say so explicitly in the README and provide a rationale.