update box_overlaps.py to fix numpy data type.

widerface_evaluate/box_overlaps.py

@@ -12,7 +12,7 @@ def bbox_overlaps(boxes, query_boxes):
     """
     N = boxes.shape[0]
     K = query_boxes.shape[0]
-    overlaps = np.zeros((N, K), dtype=np.float)
+    overlaps = np.zeros((N, K), dtype=np.float32)
     
     box_area = (
         (query_boxes[:, 2] - query_boxes[:, 0] + 1) *