Correction de "Toutes les fermetures implémentent FnOne" dans la section 13.1

[luidnel-maignan]

• I have checked the latest french-release branch to see if this has already been fixed
• I have searched existing issues and pull requests for duplicates

URL to the section(s) of the book with this problem:
https://jimskapt.github.io/rust-book-fr/ch13-01-closures.html

Description of the problem:
On y lit "FnOne"

Suggested fix:
Remplacer par "FnOnce"