fixed line too long (yamllint) for cron.yml

ansible/roles/http/tasks/cron.yml

@@ -5,5 +5,6 @@
     name: certbot_renew
     special_time: weekly
     job: |
-      certbot renew --pre-hook "systemctl stop nginx" --post-hook "systemctl start nginx"
+      certbot renew --pre-hook "systemctl stop nginx" \
+       --post-hook "systemctl start nginx"
   tags: cron