Added literal float to improve precision

according to #2922 I added missing float literals to improve the accuracy of the result.

If sensorValue = 1:

Before: voltage = 4

Now: voltage = 4.88

libraries/Bridge/examples/TemperatureWebPanel/TemperatureWebPanel.ino

@@ -98,9 +98,9 @@ void loop() {
       Serial.println(timeString);
       int sensorValue = analogRead(A1);
       // convert the reading to millivolts:
-      float voltage = sensorValue *  (5000 / 1024);
+      float voltage = sensorValue * (5000.0f / 1024.0f);
       // convert the millivolts to temperature celsius:
-      float temperature = (voltage - 500) / 10;
+      float temperature = (voltage - 500.0f) / 10.0f;
       // print the temperature:
       client.print("Current time on the Yún: ");
       client.println(timeString);