Fix compilation warning

Author: cparata

library.properties

@@ -1,5 +1,5 @@
 name=STM32duino HTS221
-version=1.0.2
+version=1.0.3
 author=AST, Wi6Labs
 maintainer=stm32duino
 sentence=Capacitive digital sensor for relative humidity and temperature.

src/HTS221Sensor.h

@@ -114,7 +114,7 @@ class HTS221Sensor
       dev_i2c->beginTransmission(((uint8_t)(((address) >> 1) & 0x7F)));
 
       dev_i2c->write(RegisterAddr);
-      for (int i = 0 ; i < NumByteToWrite ; i++)
+      for (uint16_t i = 0 ; i < NumByteToWrite ; i++)
         dev_i2c->write(pBuffer[i]);
 
       dev_i2c->endTransmission(true);