fix(deps): update rust crate uart_16550 to 0.4.0

Author: renovate[bot]

Cargo.toml

@@ -9,7 +9,7 @@ lazy_static = { version = "1.4.0", features = ["spin_no_std"] }
 spin = "0.5.2"
 volatile = "=0.2.6"
 x86_64 = "0.15.0"
-uart_16550 = "0.3.0"
+uart_16550 = "0.4.0"
 pic8259 = "0.11.0"
 pc-keyboard = "0.5.0"
 linked_list_allocator = "0.9.0"