Remove extern crate statements

https://doc.rust-lang.org/edition-guide/rust-2018/module-system/path-clarity.html

src/library.rs

@@ -5,6 +5,7 @@ use std::path::PathBuf;
 use std::sync::{Arc, RwLock, RwLockReadGuard};
 use std::thread;
 
+use log::{debug, error, info};
 use serde::de::DeserializeOwned;
 use serde::Serialize;