fix typo in classification pruning tutorial

dygraph/tutorials/slim/prune/image_classification/mobilenetv2_train.py

@@ -32,7 +32,7 @@ eval_dataset = pdx.datasets.ImageNet(
 # 初始化模型，并进行训练
 # 可使用VisualDL查看训练指标，参考https://github.com/PaddlePaddle/PaddleX/tree/release/2.0-rc/tutorials/train#visualdl可视化训练指标
 num_classes = len(train_dataset.labels)
-model = pdx.models.MobileNetV3_large(num_classes=num_classes)
+model = pdx.models.MobileNetV2(num_classes=num_classes)
 
 # API说明：https://github.com/PaddlePaddle/PaddleX/blob/95c53dec89ab0f3769330fa445c6d9213986ca5f/paddlex/cv/models/classifier.py#L153
 # 各参数介绍与调整说明：https://paddlex.readthedocs.io/zh_CN/develop/appendix/parameters.html