Remove usage of extern keyword

build.rs

@@ -1,6 +1,3 @@
-extern crate serde_cbor;
-extern crate serde_json;
-
 use std::fs::File;
 use std::env;
 

lib/src/color.rs

@@ -1,4 +1,5 @@
 use std::{convert::From, fmt};
+use serde_derive::Serialize;
 
 #[derive(Serialize, Clone)]
 pub struct RGB {

lib/src/weights.rs

@@ -1,4 +1,3 @@
-extern crate wasm_bindgen;
 use crate::color;
 
 use wasm_bindgen::{prelude::*};

src/utils.rs

@@ -1,7 +1,6 @@
-extern crate serde_cbor;
-
 use pigmnts::color::{LAB, RGB};
 use std::collections::HashMap;
+use lazy_static::lazy_static;
 
 /// Coverts a hex string to RGB color
 fn hex_to_rgb(s: &str) -> RGB {