Release 1.6.3 (#325)

diff --git a/setup.py b/setup.py
index ef9bb51..b2eb598 100644
--- a/setup.py
+++ b/setup.py
@@ -31,7 +31,7 @@
 
 setup(
     name='google-auth',
-    version='1.6.2',
+    version='1.6.3',
     author='Google Cloud Platform',
     author_email='jonwayne+google-auth@google.com',
     description='Google Authentication Library',