Update publish script skipping versions

Instead of only checking the latest version check the list of recently
published versions to determine if a version is already published.

scripts/publish.rs

@@ -421,15 +421,16 @@ fn publish(krate: &Crate) -> bool {
 
  // First make sure the crate isn't already published at this version. This
  // script may be re-run and there's no need to re-attempt previous work.
- let output = cmd_output(
- Command::new("curl").arg(&format!("https://crates.io/api/v1/crates/{}", krate.name)),
- );
+ let output = cmd_output(Command::new("curl").arg(&format!(
+ "https://crates.io/api/v1/crates/{}/versions",
+ krate.name
+ )));
  if output.status.success()
  && String::from_utf8_lossy(&output.stdout)
- .contains(&format!("\"newest_version\":\"{}\"", krate.version))
+ .contains(&format!("\"num\":\"{}\"", krate.version))
  {
  println!(
- "skip publish {} because {} is latest version",
+ "skip publish {} because {} is already published",
  krate.name, krate.version,
  );
  return true;