Fix alternative i2c implementation

The alternative I2C implementation takes a non-const data pointer for its write,
thus we need to cast away constness to fix the compiler's warning which is treated
as error with the default arduino settings.

sensirion_hw_i2c_implementation.cpp

@@ -58,19 +58,19 @@ void sensirion_i2c_release(void)
 {
 }
 
-int8_t sensirion_i2c_read(uint8_t address, u8* data, uint16_t count)
+int8_t sensirion_i2c_read(uint8_t address, uint8_t *data, uint16_t count)
 {
     return I2c.read(address, count, data);
 }
 
-int8_t sensirion_i2c_write(uint8_t address, const u8* data, uint16_t count)
+int8_t sensirion_i2c_write(uint8_t address, const uint8_t *data, uint16_t count)
 {
     // the API doesn't forsee calls without register, so we'll use the first
     // byte as "register", and pass the rest as data argument
     if (count == 0) {
       return 0;
     }
-    return I2c.write(address, data[0], data + 1, count - 1);
+    return I2c.write(address, data[0], (uint8_t *)(data + 1), count - 1);
 }
 
 #else /* SPS30_USE_ALT_I2C */