fix(deps): update rust crate bitflags to v2

Author: renovate[bot]

uart8250/Cargo.toml

@@ -14,7 +14,7 @@ readme = "README.md"
 # See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
 
 [dependencies]
-bitflags = "1"
+bitflags = "2"
 embedded-hal = { version = "0.2.7", optional = true }
 nb = { version = "1.0.0", optional = true }
 volatile-register = "0.2"