Fix Mailu admin container DNS conflict with OpenLDAP admin

roles/docker/templates/compose-files/mailu.yml.j2

@@ -69,6 +69,10 @@ services:
     volumes:
       - "./data:/data"
       - "./dkim:/dkim"
+    networks:
+      default:
+        aliases:
+          - admin.mailu
     depends_on:
       - redis
       - resolver

roles/docker/templates/mailu/env.j2

@@ -166,6 +166,12 @@ DEFAULT_SPAM_THRESHOLD=80
 # This is a mandatory setting for using the RESTful API.
 API_TOKEN=
 
+###################################
+# Container address settings
+###################################
+
+ADMIN_ADDRESS=admin.mailu
+
 ###################################
 # Database settings
 ###################################