cargo-deny flagged this for us:

[2022/08/22 14:19:27.832] = Announcement: https://github.com/ogham/rust-ansi-term/issues/72
[2022/08/22 14:19:27.832] = Solution: No safe upgrade is available!
[2022/08/22 14:19:27.832] = ansi_term v0.12.1
[2022/08/22 14:19:27.832] └── pretty_assertions v1.2.1
[2022/08/22 14:19:27.832] └── (dev) mongodb v2.4.0

This is a dev dependency, just used for pretty_assertions in tests, so I think a reasonable course of action here is to file a ticket against that crate and add the unmaintained advisory to the allowlist.