Prepare 0.4.0 release

Bumped version in Cargo.toml.

Author: sophokles73

Cargo.lock

@@ -30,7 +30,7 @@ name = "up-rust"
 readme = "README.md"
 repository = "https://github.com/eclipse-uprotocol/up-rust"
 rust-version = "1.74.1"
-version = "0.3.0"
+version = "0.4.0"
 
 [features]
 default = ["communication"]