haproxy: remove '.sh' from certbot_renew cron script

apparently run-parts (which is used in the main crontab in busybox),
doesn't accept any filenames that don't have the format:
"^[a-zA-Z0-9_-]+$)"

roles/haproxy/tasks/main.yml

@@ -34,8 +34,8 @@
 
   - name: add certbot autorenew cron job
     template:
-      src: templates/certbot_renew_cron.sh.j2
-      dest: /etc/periodic/weekly/certbot_renew.sh
+      src: templates/certbot_renew_cron.j2
+      dest: /etc/periodic/weekly/certbot_renew
       mode: 0755