Challenge 25: Verify the safety of `VecDeque` functions

[thanhnguyen-aws]

Runbook Link

https://model-checking..io/verify-rust-std/challenges/0025-vecdeque.html

[vrindisbacher]

Hey there - following the book link gives me a 404. Is this still a challenge?

[tautschnig]

It will become one, we just haven’t yet received approval from the rewards committee on #269.