check for ipv6_enabled in the compose template

Checking only `ipv6` isn't sufficient, because it has a default value.

setup/flavors/compose/docker-compose.yml

@@ -26,7 +26,7 @@ services:
     {% if bind4 %}
       - "{{ bind4 }}:{{ port }}:{{ port }}"
     {% endif %}
-    {% if bind6 %}
+    {% if ipv6_enabled and bind6 %}
       - "{{ bind6 }}:{{ port }}:{{ port }}"
     {% endif %}
     {% endfor %}