fix the model_zoo

docs/appendix/model_zoo.md

@@ -27,7 +27,7 @@
 | DenseNet161| 118.0MB  | 22.79690       | 78.6     | 94.1     |
 | DenseNet201|  84.1MB   | 25.26089       | 77.6     | 93.7     |
 | ShuffleNetV2 | 10.2MB   | 15.40138        | 68.8     | 88.5     |
-| HRNet_W18 | 21.29MB |  | 45.25514 | 93.4 |
+| HRNet_W18 | 21.29MB |45.25514  | 76.9 | 93.4 |
 
 ## 目标检测模型