fix PicoDet_layout_1x_table train config (#2895)

paddlex/repo_apis/PaddleDetection_api/configs/PicoDet_layout_1x_table.yaml

@@ -15,7 +15,7 @@ print_params: false
 
 # Dataset
 metric: COCO
-num_classes: 5
+num_classes: 1
 
 worker_num: 8