here is a real world example of shell commands that we use in Drone to setup an ssh key. The below commands are verified and confirmed to work, as long as you setup your secret properly.
The error message in your previous post states that it fails because it is an invalid format. Notice in the example I posted above that we quote the ssh key before writing to a file so that it preserves newlines. This is important and is omitted in your example above, which could explain the failure.
are you certain your token has write access to the repository? It looks like the repository is being successfully cloned which would imply the secret is successfully being used to pull the repository … if pull is successful, but push fails, it would imply the token lacks permission