fix scope program for export inference

paddlex/cv/models/base.py

@@ -356,6 +356,7 @@ class BaseAPI:
     def export_inference_model(self, save_dir):
         test_input_names = [var.name for var in list(self.test_inputs.values())]
         test_outputs = list(self.test_outputs.values())
+        with fluid.scope_guard(self.scope):
             if self.__class__.__name__ == 'MaskRCNN':
                 from paddlex.utils.save import save_mask_inference_model
                 save_mask_inference_model(