Update Ackee Docker Compose to include MongoDB data volume

- Added a volume for MongoDB to persist data across container restarts.
- Cleaned up the Docker Compose file by removing unnecessary blank lines.

blueprints/ackee/docker-compose.yml

@@ -1,8 +1,5 @@
-
-
 version: "3"
 
-
 services:
   ackee:
     image: electerious/ackee:3.4.2
@@ -17,5 +14,10 @@ services:
     image: mongo:4
     environment:
       - MONGO_INITDB_ROOT_PASSWORD=${MONGO_INITDB_ROOT_PASSWORD}
-  
+    volumes:
+      - mongo-data:/data/db
+
+
+volumes:
+  mongo-data: