update idm.py.

Signed-off-by: Sgr A* VMT <1611902585@qq.com>

idm.py

@@ -885,9 +885,9 @@ class IDMProbe:
         old_offset = self.model.offset
         self.model.offset += offset
         self.model.save(self, False)
-        gcmd.respond_info("IDM model offset has been updated to {self.model.offset}.\n"
+        gcmd.respond_info("IDM model offset has been updated to {}.\n"
                 "You must run the SAVE_CONFIG command now to update the\n"
-                "printer config file and restart the printer.")
+                "printer config file and restart the printer.".format(self.model.offset))
         self.model.offset = old_offset
 
 class IDMModel: