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>

event_monitor/src/lib.rs

@@ -3,9 +3,7 @@
 // SPDX-License-Identifier: Apache-2.0
 //
 
-#[macro_use]
-extern crate serde_derive;
-
+use serde::Serialize;
 use std::borrow::Cow;
 use std::collections::HashMap;
 use std::fs::File;