fixing to docutils==0.16

Change-Id: I98602bfb74ff422b14ce031b8025995226a56958
diff --git a/VERSION b/VERSION
index 37c2961..2c9b4ef 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.7.2
+2.7.3
diff --git a/requirements.txt b/requirements.txt
index 3a3044c..2053e92 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -2,6 +2,7 @@
 actdiag~=2.0.0
 blockdiag~=1.5.4
 doc8~=0.8.0
+docutils==0.16
 nwdiag~=2.0.0
 recommonmark~=0.6.0
 seqdiag~=2.0.0