Updated INF to 100000.0 to be in line with original YOLOX implementation. (#7778)

Author: jovialio

mmdet/core/bbox/assigners/sim_ota_assigner.py

@@ -119,7 +119,7 @@ def _assign(self,
         Returns:
             :obj:`AssignResult`: The assigned result.
         """
-        INF = 100000000
+        INF = 100000.0
         num_gt = gt_bboxes.size(0)
         num_bboxes = decoded_bboxes.size(0)