In `ScalarPrimitive`, [this line](https://github.com/RustCrypto/traits/blob/f1ae691906681e7399db5a4088c24b4a44faa712/elliptic-curve/src/scalar/primitive.rs#L400) should use `base16ct::mixed`
In
ScalarPrimitive, this line should usebase16ct::mixed