Cast `co2` to uint32_t to avoid overflow

ampel-firmware/co2_sensor.cpp

@@ -8,7 +8,7 @@ namespace config {
   uint16_t co2_calibration_level = ATMOSPHERIC_CO2_CONCENTRATION; // [ppm]
   int8_t max_deviation_during_calibration = 30; // [ppm]
   int8_t enough_stable_measurements = 60;
-  const uint8_t max_deviation_during_accl = 20; // [%]
+  const uint8_t max_deviation_during_bootup = 20; // [%]
 #ifdef TEMPERATURE_OFFSET
   // Residual heat from CO2 sensor seems to be high enough to change the temperature reading. How much should it be offset?
   // NOTE: Sign isn't relevant. The returned temperature will always be shifted down.
@@ -135,7 +135,7 @@ namespace sensor {
     last_co2 = co2;
     // We assume the sensor has acclimated to the environment if measurements
     // change less than a specified percentage of the current value.
-    return (co2 > 0 && (100 * delta / config::max_deviation_during_accl) < co2);
+    return (co2 > 0 && delta < ((uint32_t)co2 * config::max_deviation_during_bootup / 100));
   }
 
   bool countStableMeasurements() {