Fix typo.

PiperOrigin-RevId: 378785927

Author: fredrec

tensorflow_model_optimization/python/core/sparsity/keras/tools/evaluate_pruning.py

@@ -19,7 +19,7 @@
 
 This tool is intented to produce sparsified models for evaluating the
 performance benefits (model size, inference time, …) of pruning. Since the
-sparsity is applied in one shot, without retrainig, the accuracy of the
+sparsity is applied in one shot, without retraining, the accuracy of the
 resulting model will be severly degraded.
 """