fix all warnings

rust/src/hal/mod.rs

@@ -51,11 +51,6 @@ const TANK_MULTI_SAMPLE: usize = 11;
 
 pub static I2C_DRIVER: Lazy<Mutex<I2cDriver<'static>>> = Lazy::new(PlantHal::create_i2c);
 
-#[non_exhaustive]
-struct V3Constants;
-
-impl V3Constants {}
-
 const X25: crc::Crc<u16> = crc::Crc::<u16>::new(&crc::CRC_16_IBM_SDLC);
 
 fn deep_sleep(duration_in_ms: u64) -> ! {
@@ -132,6 +127,7 @@ pub trait BoardInteraction<'a> {
     fn set_config(&mut self, config: PlantControllerConfig) -> Result<()>;
 }
 
+#[allow(dead_code)]
 pub struct FreePeripherals {
     pub gpio0: Gpio0,
     pub gpio1: Gpio1,