How do I allow sede::{Serialize, Deserialize} as external types?

It would be best to do the same thing that portable-atomic does:

• For CI / tidy / check-external-types: https://github.com/taiki-e/portable-atomic/blob/975827a60b3390f57299a35c6af0ef4014c3456d/Cargo.toml#L27
• For CI / tidy / deny: https://github.com/taiki-e/portable-atomic/blob/975827a60b3390f57299a35c6af0ef4014c3456d/.deny.toml#L23-L24

Is it ok now?

Could you address the remaining CI failures?
Since all errors are in diff form, I think applying the fixes will be easy.
https://github.com/taiki-e/portable-atomic-util/actions/runs/24204227961/job/70655797351?pr=2

Getting this to merge was a learning experience 😂, in a positive way though.

Published in 0.2.7.