Update the versioning on the docker-compose template

Some versions of docker-compose will break with the new addition of
name parameters without this.

tools/docker-compose/ansible/roles/sources/templates/docker-compose.yml.j2

@@ -1,5 +1,5 @@
 ---
-version: '2'
+version: '2.1'
 services:
 {% for i in range(cluster_node_count|int) %}
   {% set container_postfix = loop.index %}