gitoxide does not detect SHA-1 collision attacks

gitoxide is an implementation of git written in Rust. Before 0.42.0, gitoxide uses SHA-1 hash implementations without any collision detection, leaving it vulnerable to hash collision attacks. gitoxide uses the sha1_smol or sha1 crate, both of which implement standard SHA-1 without any mitigations for collision attacks. This means that two distinct Git objects with colliding SHA-1 hashes would break the Git object model and integrity checks when used with gitoxide. This vulnerability is fixed in 0.42.0.