Fix get best ratios.

paddleslim/prune/sensitive.py

@@ -221,6 +221,7 @@ def get_ratios_by_loss(sensitivities, loss):
     """
     ratios = {}
     for param, losses in sensitivities.items():
+        losses = losses.items()
         losses.sort()
         for i in range(len(losses))[::-1]:
             if losses[i][1] <= loss: