Auto merge of #127931 - GuillaumeGomez:switch-to-rinja, r=notriddle

Replace askama with rinja

Another askama maintainer and myself forked it and named the fork rinja. The whole difference is explained in this [blog post](https://blog.guillaume-gomez.fr/articles/2024-07-16+docs.rs+switching+jinja+template+framework+from+tera+to+rinja) (not publicly released yet, waiting for docs.rs to deploy the new version using it before). But in short, rinja got a lot of improvements and compiles faster, so I think it's definitely worth it to use it in rustdoc as well.

r? `@notriddle`

Author: bors