FIX: the load filament steps shown fault

jira: [STUDIO-9684]
Change-Id: Ic238993302156788200482ed34e3092b9ab94dfd
(cherry picked from commit f8b4949353fbb4cead3249d5e8f6beb06859164c)

src/slic3r/GUI/DeviceManager.hpp

@@ -749,6 +749,7 @@ public:
     /*extruder*/
     [[nodiscard]] bool is_nozzle_flow_type_supported() const { return is_enable_np; };
     [[nodiscard]] NozzleFlowType get_nozzle_flow_type(int extruder_id) const;
+    [[nodiscard]] const Extder& get_current_extruder() const;
 
     //new fan data
     AirDuctData m_air_duct_data;