deploy: Use alternative format for staging

Followup to e3db010
where this one was missed.  Copy-pasting that git log
for ease of consumption:

Same motivation as ostreedev/ostree-rs-ext#604

Because fetching from a registry with the default sigverify is
the 90% case default, when we see this (and are formatting for
human consumption), use the "alternate" formatting to just
display the image name.

This makes the ostree stuff *much* less in the user's face
in the default path.

Signed-off-by: Colin Walters <walters@verbum.org>

lib/src/deploy.rs

@@ -265,7 +265,7 @@ pub(crate) async fn stage(
  )
  .await?;
  crate::deploy::cleanup(sysroot).await?;
- println!("Queued for next boot: {}", spec.image);
+ println!("Queued for next boot: {:#}", spec.image);
  if let Some(version) = image.version.as_deref() {
  println!(" Version: {version}");
  }