chore(deps): bump assets/chezmoi.io/themes/book

Bumps [assets/chezmoi.io/themes/book](https://github.com/alex-shpak/hugo-book) from `9d4916f` to `8bb6d7e`.
- [Release notes](https://github.com/alex-shpak/hugo-book/releases)
- [Commits](alex-shpak/hugo-book@9d4916f...8bb6d7e)

---
updated-dependencies:
- dependency-name: assets/chezmoi.io/themes/book
  dependency-type: direct:production
...

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