clippy: fix clippy warnings

Software/MainBoard/rust/src/plant_state.rs

@@ -1,6 +1,5 @@
 use crate::hal::Moistures;
 use crate::{config::PlantConfig, hal::HAL, in_time_range};
-use alloc::string::String;
 use chrono::{DateTime, TimeDelta, Utc};
 use chrono_tz::Tz;
 use serde::{Deserialize, Serialize};
@@ -14,8 +13,7 @@ pub enum MoistureSensorError {
     MissingMessage,
     NotExpectedMessage { hz: f32 },
     ShortCircuit { hz: f32, max: f32 },
-    OpenLoop { hz: f32, min: f32 },
-    BoardError { message: String },
+    OpenLoop { hz: f32, min: f32 }
 }
 
 #[derive(Debug, PartialEq, Serialize)]