Update word2vec.py

bug fix for contrib.deprecated eliminatation in tf version 12.

tutorials/embedding/word2vec.py

@@ -365,7 +365,7 @@ class Word2Vec(object):
       self._word2id[w] = i
     true_logits, sampled_logits = self.forward(examples, labels)
     loss = self.nce_loss(true_logits, sampled_logits)
-    tf.contrib.deprecated.scalar_summary("NCE loss", loss)
+    tf.scalar_summary("NCE loss", loss)
     self._loss = loss
     self.optimize(loss)