Add 'linear' and maybe add serde ?

[ethereumdegen]

I just want to say amazing crate. In order to use it in my particular usecase, i had to vendor it and make some changes.

use serde::{Deserialize, Serialize};

#[allow(missing_docs)]
#[derive(Debug, Copy, Clone, PartialEq, Serialize, Deserialize,Default)]
pub enum EaseFunction {
	#[default]
	Linear, 


    QuadraticIn,
    QuadraticOut,

...

so imo it would be nice if

1. there was a 'feature' that was optional to this crate to add serde like this
2. you also added the Linear case and made it 'default' like i do above

just some tiny improvements that prob make sense . thanks

[bvssvni]

Yeah, we can add Serde support through a Cargo feature flag.