fix format

configs/ppyolo/ppyolo_voc.yml

-architecture: YOLOv3                                                                                                                               
-use_gpu: true                                                                                                                                      
-max_iters: 70000                                                                                                                                   
-log_smooth_window: 20                                                                                                                              
-log_iter: 20                                                                                                                                       
-save_dir: output                                                                                                                                   
-snapshot_iter: 10000                                                                                                                               
-metric: VOC                                                                                                                                        
-pretrain_weights: https://paddle-imagenet-models-name.bj.bcebos.com/ResNet50_vd_ssld_pretrained.tar                                                
-weights: output/ppyolo/model_final                                                                                                                 
-num_classes: 20                                                                                                                                    
-use_fine_grained_loss: true                                                                                                                        
-use_ema: true                                                                                                                                      
-ema_decay: 0.9998 
+architecture: YOLOv3
+use_gpu: true
+max_iters: 70000
+log_smooth_window: 20
+log_iter: 20
+save_dir: output
+snapshot_iter: 10000
+metric: VOC
+pretrain_weights: https://paddle-imagenet-models-name.bj.bcebos.com/ResNet50_vd_ssld_pretrained.tar
+weights: output/ppyolo/model_final
+num_classes: 20
+use_fine_grained_loss: true
+use_ema: true
+ema_decay: 0.9998
 
 YOLOv3:
   backbone: ResNet
@@ -89,29 +89,29 @@ OptimizerBuilder:
     type: L2
 
 _READER_: 'ppyolo_reader.yml'
-TrainReader:                                                                                                                                       
-  dataset:                                                                                                                                         
-    !VOCDataSet                                                                                                                                    
-    dataset_dir: dataset/voc                                                                                                            
-    anno_path: trainval.txt                                                                                                                        
-    use_default_label: true                                                                                                                        
-    with_background: false                                                                                                                         
-  mixup_epoch: 350                                                                                                                                 
+TrainReader:
+  dataset:
+    !VOCDataSet
+    dataset_dir: dataset/voc
+    anno_path: trainval.txt
+    use_default_label: true
+    with_background: false
+  mixup_epoch: 350
   batch_size: 12
-                                                                                                                                                   
-EvalReader:                                                                                                                                        
-  inputs_def:                                                                                                                                      
-    fields: ['image', 'im_size', 'im_id', 'gt_bbox', 'gt_class', 'is_difficult']                                                                   
-    num_max_boxes: 50                                                                                                                              
-  dataset:                                                                                                                                         
-    !VOCDataSet                                                                                                                                    
-    dataset_dir: dataset/voc                                                                                                            
-    anno_path: test.txt                                                                                                                            
-    use_default_label: true                                                                                                                        
-    with_background: false                                                                                                                         
-                                                                                                                                                   
-TestReader:                                                                                                                                        
-  dataset:                                                                                                                                         
-    !ImageFolder                                                                                                                                   
-    use_default_label: true                                                                                                                        
-    with_background: false 
+
+EvalReader:
+  inputs_def:
+    fields: ['image', 'im_size', 'im_id', 'gt_bbox', 'gt_class', 'is_difficult']
+    num_max_boxes: 50
+  dataset:
+    !VOCDataSet
+    dataset_dir: dataset/voc
+    anno_path: test.txt
+    use_default_label: true
+    with_background: false
+
+TestReader:
+  dataset:
+    !ImageFolder
+    use_default_label: true
+    with_background: false