Bump metadata.json 11.6.0 for stable/train release

Needed by [1] to make a stable/train release for tripleo repos.

[1] I7672f167a2279d7f00dd95b86ec83a8233e8bb63

Change-Id: Ice881206b3f413e0a22dcbfd557a7d8224b3449c

metadata.json

@@ -1,6 +1,6 @@
 {
   "name": "openstack-tripleo",
-  "version": "11.5.0",
+  "version": "11.6.0",
   "author": "OpenStack Contributors",
   "summary": "Puppet module for TripleO",
   "license": "Apache-2.0",