feat: generate secure secret key and prevent default

docker-compose.prod.yml

@@ -27,6 +27,7 @@ services:
     environment:
       - MONGO_URL=mongodb://user:user-password@db:27017/odyssey-test
       - DOCKER_NETWORK=linux-odyssey-players
+      - SECRET_KEY=${SECRET_KEY}
 
   analytics:
     image: lancatlin/linux-odyssey:analytics