Merge pull request #1481 from FlyingQianMM/develop_qh

fix VarifocalLoss import error

paddlex/ppdet/modeling/losses/__init__.py

@@ -25,6 +25,7 @@ from . import fairmot_loss
 from . import gfocal_loss
 from . import detr_loss
 from . import sparsercnn_loss
+from . import varifocal_loss
 
 from .yolo_loss import *
 from .iou_aware_loss import *
@@ -39,3 +40,4 @@ from .fairmot_loss import *
 from .gfocal_loss import *
 from .detr_loss import *
 from .sparsercnn_loss import *
+from .varifocal_loss import *