fix all compiler warnings

rust/src/plant_state.rs

@@ -1,10 +1,12 @@
+use crate::{
+    config::PlantConfig,
+    hal::{Sensor, HAL},
+    in_time_range,
+};
 use chrono::{DateTime, TimeDelta, Utc};
 use chrono_tz::Tz;
 use serde::{Deserialize, Serialize};
 
-use crate::hal::{BoardInteraction, Sensor, HAL};
-use crate::{config::PlantConfig, in_time_range};
-
 const MOIST_SENSOR_MAX_FREQUENCY: f32 = 7500.; // 60kHz (500Hz margin)
 const MOIST_SENSOR_MIN_FREQUENCY: f32 = 150.; // this is really, really dry, think like cactus levels