SSH access is granted via an RSA key stored in build/certificates/downloads-hostgator.mixxx.org.key.
To rotate this key, generate a new RSA key with a strong password (e.g. 32 character randomly generated).
ssh-keygen -t rsa -b 4096 -f downloads-hostgator.mixxx.org.key
Copy the public key to $HOME/.ssh/authorized_keys, replacing the old file to remove access for the current key.
Encrypt the password using travis encrypt and update .travis.yml.
travis encrypt DOWNLOADS_HOSTGATOR_DOT_MIXXX_DOT_ORG_KEY_PASSWORD=hunter2 -r mixxxdj/mixxx