Make room for pluralize patch

Change-Id: I8f53fcfe8141050fc5ecbf36cde6e6f8855ad67b
diff --git a/containers/xos/pip_requirements.txt b/containers/xos/pip_requirements.txt
index 5f2e5eb..720ba8d 100644
--- a/containers/xos/pip_requirements.txt
+++ b/containers/xos/pip_requirements.txt
@@ -95,6 +95,7 @@
 oslo.utils==3.16.0
 osprofiler==1.4.0
 paramiko==2.0.2
+pattern==2.6
 pbr==1.10.0
 pika==0.10.0
 pika-pool==0.1.3