removed network for container cron, not needed

removes the necessity for a useless network <projectname>_default

docker-compose.override.yml

@@ -3,6 +3,7 @@ services:
   cron:
     image: bryanpedini/dockercron:${CRON_VERSION}
     restart: unless-stopped
+    network_mode: none
     volumes:
       - /var/run/docker.sock:/var/run/docker.sock
       - ${CRON_CRONTAB}:/crontab/root