Using a newer xosmigrate library

Change-Id: Ia34ff4f0e0e3aa41c6c4039bae4463aa8d217ed7
diff --git a/Makefile b/Makefile
index af0e6f6..737cbe1 100644
--- a/Makefile
+++ b/Makefile
@@ -60,7 +60,7 @@
 venv-service:
 	virtualenv $@;\
     source ./$@/bin/activate ; set -u ;\
-    pip install -r requirements.txt xosmigrate~=3.2.1
+    pip install -r requirements.txt xosmigrate~=3.2.6
 
 create-migration: venv-service
 	source ./venv-service/bin/activate; set -u;\