Fix: onNewVoltage: Unit is "mV"

src/ATBAPP/ATBDeviceControllerPlugin.cpp

@@ -647,7 +647,7 @@ void ATBDeviceControllerPlugin::onNewVoltage(uint32_t voltage)
     json = JSON::objectBuilder()
                   ->set("Name", "batt")
                   ->set("Value", voltageString)
-                  ->set("Unit", "V")
+                  ->set("Unit", "mV")
             ->create();