Update serial_test requirement from 3.0.0 to 4.0.1

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@v3.0.0...v4.0.1)

---
updated-dependencies:
- dependency-name: serial_test
  dependency-version: 4.0.1
  dependency-type: direct:production
...

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

Author: dependabot[bot]

Cargo.toml

@@ -58,7 +58,7 @@ btrfs-backup = { path = ".", features = ["test"] }
 glob = "0.3.1"
 goblin = "0.10.0"
 memmap = "0.7.0"
-serial_test = "3.0.0"
+serial_test = "4.0.1"
 tempfile = "3.3.0"
 time-macros = "0.2.24"