Update Configuration_adv.h

Increase Z_HOME_RETRACT_MM to 2mm default to avoid end stop not switching during retract.

Marlin/Configuration_adv.h

@@ -215,7 +215,7 @@
 //homing hits the endstop, then retracts by this distance, before it tries to slowly bump again:
 #define X_HOME_RETRACT_MM 5
 #define Y_HOME_RETRACT_MM 5
-#define Z_HOME_RETRACT_MM 1
+#define Z_HOME_RETRACT_MM 2
 //#define QUICK_HOME  //if this is defined, if both x and y are to be homed, a diagonal move will be performed initially.
 
 #define AXIS_RELATIVE_MODES {false, false, false, false}