Allow unused stuff in fmt.rs

embassy-stm32f4/src/fmt.rs

@@ -1,5 +1,6 @@
 #![macro_use]
 #![allow(clippy::module_inception)]
+#![allow(unused)]
 
 #[cfg(all(feature = "defmt", feature = "log"))]
 compile_error!("You may not enable both `defmt` and `log` features.");