sns: set pH decimals to 3 (#2306)

code/espurna/sensor.cpp

@@ -574,6 +574,8 @@ unsigned char _sensorUnitDecimals(sensor::Unit unit) {
             return 1;
         case sensor::Unit::UltravioletIndex:
             return 3;
+        case sensor::Unit::Ph:
+            return 3;
         case sensor::Unit::None:
         default:
             return 0;

code/espurna/sensor.h

@@ -57,6 +57,7 @@ enum class Unit : int {
     MicrosievertPerHour,       // 2nd unit of local dose rate (Geiger counting)
     Meter,
     Hertz,
+    Ph,
     Max_
 };
 

code/espurna/sensors/BaseSensor.h

@@ -135,6 +135,8 @@ class BaseSensor {
                     return sensor::Unit::Meter;
                 case MAGNITUDE_FREQUENCY:
                     return sensor::Unit::Hertz;
+                case MAGNITUDE_PH:
+                    return sensor::Unit::Ph;
                 default:
                     return sensor::Unit::None;
             }