made changes in tanks controller

src/controllers/tanksController.js

@@ -163,7 +163,7 @@ exports.updateTanklevels = async (req, reply) => {
      // let waterLevel = parseInt(tank.waterlevel.replace(/,/g, ''), 10);
 
       const intervalId = setInterval(async function () {
-        let waterLevel = parseInt(tank.waterlevel.replace(/,/g, ''), 10);
+        const waterLevel = parseInt(tank.waterlevel.replace(/,/g, ''), 10);
         console.log(waterLevel)
         const motorStatus = tank.motor_status
       const newWaterLevel = Math.floor(waterLevel - 200);