Remove extern crate statements

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

src/spotify_worker.rs

@@ -15,6 +15,7 @@ use librespot_core::session::Session;
 use librespot_core::spotify_id::{SpotifyAudioType, SpotifyId};
 use librespot_playback::mixer::Mixer;
 use librespot_playback::player::{Player, PlayerEvent as LibrespotPlayerEvent};
+use log::{debug, error, info, warn};
 use std::time::Duration;
 use std::{pin::Pin, time::SystemTime};