Fix crash in manage_response

The watchdog needs to be kicked in the for(;;) loop.
This is usually done by calling manage_heater before
manage_inactivity.

Firmware/mmu2.cpp

@@ -511,7 +511,7 @@ void MMU2::manage_response(const bool move_axes, const bool turn_off_nozzle) {
         // - still running -> wait normally in idle()
         // - failed -> then do the safety moves on the printer like before
         // - finished ok -> proceed with reading other commands
-        
+        manage_heater();
         // @@TODO this needs verification - we need something which matches Marlin2's idle()
         manage_inactivity(true); // calls LogicStep() and remembers its return status