Update book-store.rs to add missing test f808b5a4-e01f-4c0d-881f-f7b90d9739da

Add missing test f808b5a4-e01f-4c0d-881f-f7b90d9739da from https:/github.com/exercism/problem-specifications/blob/main/exercises/book-store/canonical-data.json (Update book-store.rs by hkBst · Pull Request #1644 · exercism/rust · GitHub)