Fix typo in serving method name (#175)

* Fix typo in serving method name

The correct method name is  "tensorflow/serving/regress" - https://www.tensorflow.org/tfx/serving/signature_defs

* Fix test

Author: icywang86rui

src/tf_container/proxy_client.py

@@ -31,7 +31,7 @@
 
 DEFAULT_GRPC_REQUEST_TIMEOUT_FOR_INFERENCE_ACCELERATOR = 30.0
 
-REGRESSION = 'tensorflow/serving/regression'
+REGRESSION = 'tensorflow/serving/regress'
 CLASSIFY = 'tensorflow/serving/classify'
 INFERENCE = 'tensorflow/serving/inference'
 PREDICT = 'tensorflow/serving/predict'

test/unit/test_proxy_client.py

@@ -21,7 +21,7 @@
 
 from tf_container.proxy_client import GRPCProxyClient
 
-REGRESSION = 'tensorflow/serving/regression'
+REGRESSION = 'tensorflow/serving/regress'
 INFERENCE = 'tensorflow/serving/inference'
 CLASSIFY = 'tensorflow/serving/classify'
 PREDICT = 'tensorflow/serving/predict'