Update the version range for 2.0 release.

PiperOrigin-RevId: 275075588

Author: shadowdragon89

tensorflow_serving/tools/pip_package/setup.py

@@ -33,7 +33,7 @@
 # Set when releasing a new version of TensorFlow Serving (e.g. 1.0.0).
 _VERSION = '0.0.0'
 # Have this by default be open; releasing a new version will lock to TF version
-_TF_VERSION = '>=1.2.0,<2'
+_TF_VERSION = '>=1.2.0,<3'
 _TF_VERSION_SANITIZED = _TF_VERSION.replace('-', '')
 
 project_name = 'tensorflow-serving-api'