Installation of local mirror-registry fails with error Permission denied (publickey)

Issue

• Installation of the local mirror-registry as a root user fails with the following "Permission denied (publickey)" error:

fatal: [root@<hostname>]: UNREACHABLE! => {"changed": false, "msg": "Failed to connect to the host via ssh: Warning: 
Permanently added  ‘<hostname>’ (RSA) to the list of known hosts.\r\n<hostname>: Permission denied (publickey).” “Unreachable”: true}