Fix ambiguity comparing against usize

[glueball]

I have been getting ambiguity errors due to interaction with a dependency that declares a PartialOrd for usize.

I haven't added a test for that case (would require partial ord, which then would be in effect in all the crate), but all the tests in the crate pass, and the change should not controversial enough. In addition, it prevents avoiding an unwrap;)

22 | #[derive(Serialize, Deserialize, Props, redb_derive::Value, Debug, PartialEq, Eq, PartialOrd, Ord, Clone)]
   |                                         ^^^^^^^^^^^^^^^^^^ cannot infer type
   |
   = note: multiple `impl`s satisfying `usize: std::cmp::PartialOrd<_>` found in the following crates: `actix_web`, `core`:
           - impl std::cmp::PartialOrd for usize;
           - impl std::cmp::PartialOrd<actix_web::http::header::content_length::ContentLength> for usize;

[cberner]

Thanks!