Update Italian language (#12327)

Marlin/src/lcd/language/language_it.h

 #define MSG_AUTO_HOME_X                     _UxGT("Home asse X")
 #define MSG_AUTO_HOME_Y                     _UxGT("Home asse Y")
 #define MSG_AUTO_HOME_Z                     _UxGT("Home asse Z")
+#define MSG_AUTO_Z_ALIGN                    _UxGT("Allineam.automat. Z")
 #define MSG_TMC_Z_CALIBRATION               _UxGT("Calibra Z")
 #define MSG_LEVEL_BED_HOMING                _UxGT("Home assi XYZ")
 #define MSG_LEVEL_BED_WAITING               _UxGT("Premi per iniziare")