update Rust edition 2021

Signed-off-by: Alexandra Iordache <[email protected]>

Author: Alexandra Iordache

Cargo.toml

@@ -7,7 +7,7 @@ repository = "https://github.com/rust-vmm/event-manager"
 readme = "README.md"
 authors = ["rust-vmm AWS maintainers <[email protected]>"]
 license = "Apache-2.0 OR BSD-3-Clause"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 vmm-sys-util = "0.11.0"