!2606 Update version to 0.3.1

Merge pull request !2606 from zhoufeng/update-version-to-0.3.1

setup.py

@@ -23,7 +23,7 @@ from setuptools import setup, find_packages
 from setuptools.command.egg_info import egg_info
 from setuptools.command.build_py import build_py
 
-version = '0.3.0'
+version = '0.3.1'
 
 backend_policy = os.getenv('BACKEND_POLICY')
 commit_id = os.getenv('COMMIT_ID').replace("\n", "")