cargo: Clean up serde dependencies

There is no need to include serde_derive separately,
as it can be specified as serde feature instead.

Signed-off-by: Maksym Pavlenko <pavlenko.maksym@gmail.com>

virtio-devices/Cargo.toml

@@ -23,8 +23,7 @@ net_util = { path = "../net_util" }
 pci = { path = "../pci" }
 rate_limiter = { path = "../rate_limiter" }
 seccompiler = "0.2.0"
-serde = "1.0.137"
-serde_derive = "1.0.137"
+serde = { version="1.0.137", features=["derive"] }
 serde_json = "1.0.81"
 thiserror = "1.0.31"
 versionize = "0.1.6"

virtio-devices/src/lib.rs

@@ -14,9 +14,8 @@
 extern crate event_monitor;
 #[macro_use]
 extern crate log;
-#[macro_use]
-extern crate serde_derive;
 
+use serde::{Deserialize, Serialize};
 use std::convert::TryInto;
 use std::io;