Update serial_test requirement from 2.0.0 to 3.0.0

Updates the requirements on [serial_test](https://github.com/palfrey/serial_test) to permit the latest version.
- [Release notes](https://github.com/palfrey/serial_test/releases)
- [Commits](palfrey/serial_test@v2.0.0...v3.0.0)

---
updated-dependencies:
- dependency-name: serial_test
  dependency-type: direct:production
...

Signed-off-by: dependabot[bot] <support@github.com>

Cargo.toml

@@ -50,7 +50,7 @@ uuid = {version = "1.0", default-features = false, features = ["serde"]}
 websocket-util = "0.12.0"
 
 [dev-dependencies]
-serial_test = {version = "2.0.0", default-features = false}
+serial_test = {version = "3.0.0", default-features = false}
 test-log = {version = "0.2.14", default-features = false, features = ["trace"]}
 tokio = {version = "1.13", default-features = false, features = ["rt-multi-thread", "macros"]}
 uuid = {version = "1.0", default-features = false, features = ["v4"]}