rclone: Use absolute path for ssh key

Looks like cron doesn't provide HOME directory path correctly

roles/rclone/templates/rclone.conf.j2

@@ -5,6 +5,6 @@
 type = sftp
 host = {{ host }}
 user = {{ remote_user }}
-key_file = {{ private_key | default('~/.ssh/id_ed25519') }}
+key_file = {{ private_key | default('/root/.ssh/id_ed25519') }}
 known_hosts_file = /etc/ssh/ssh_known_hosts                                    
 {% endfor %}