message: Improve readability of autogenerated passphrase
  Printing it on a separate line removes the need for quotation marks,
  which could be misinterpreted as part of the passphrase.
diff: @@ -207,10 +207,8 @@ fn encrypt(opts: AgeOptions) -> Result<(), error::EncryptError> {
  match read_or_generate_passphrase() {
  Ok(Passphrase::Typed(passphrase)) => age::Encryptor::Passphrase(passphrase),
  Ok(Passphrase::Generated(new_passphrase)) => {
  - eprintln!(
  - "Using the autogenerated passphrase '{}'.",
  - new_passphrase.expose_secret()
  - );
  + eprintln!("Using an autogenerated passphrase:");
  + eprintln!(" {}", new_passphrase.expose_secret());
  age::Encryptor::Passphrase(new_passphrase)
  }
  Err(_) => return Ok(()),
  