CORD-1392: Add package needed by new model policies

Change-Id: Ie7725772dffe2c8520d39d4fc1871664a4c9a2a9
diff --git a/containers/xos/pip_requirements.txt b/containers/xos/pip_requirements.txt
index d54cae9..ecedb5d 100644
--- a/containers/xos/pip_requirements.txt
+++ b/containers/xos/pip_requirements.txt
@@ -166,4 +166,5 @@
 wsgiref==0.1.2
 zope.interface==4.3.3
 redis==2.10.5
+astunparse==1.5.0
 git+https://github.com/sb98052/plyprotobuf