Driver, Gateway: Remove tokio 0.2 support (#118)

* Remove tokio 0.2 compat
* Remove tokio 0.2 test
* Remove tokio 0.2 CI

src/tracks/handle.rs

@@ -5,10 +5,7 @@ use crate::{
 };
 use flume::Sender;
 use std::{fmt, sync::Arc, time::Duration};
-#[cfg(not(feature = "tokio-02-marker"))]
 use tokio::sync::RwLock;
-#[cfg(feature = "tokio-02-marker")]
-use tokio_compat::sync::RwLock;
 use typemap_rev::TypeMap;
 use uuid::Uuid;