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

@@ -428,15 +428,16 @@ 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;