Fix Yogi import (#875)

seanpmorgan · seanpmorgan · commit 0682f9cbbabf · 2020-01-23T16:27:05.000-05:00
(cherry picked from commit 0a23fd2)
diff --git a/tensorflow_addons/optimizers/__init__.py b/tensorflow_addons/optimizers/__init__.py
@@ -38,3 +38,4 @@
 from tensorflow_addons.optimizers.weight_decay_optimizers import SGDW
 from tensorflow_addons.optimizers.weight_decay_optimizers import (
     extend_with_decoupled_weight_decay)
+from tensorflow_addons.optimizers.yogi import Yogi
