Revert "admin/render_readmes: Remove redundant tokio runtime" (#9889)

This reverts commit dda300e.

The relevant code was used inside a `std::thread::spawn()` block, which currently does not have an attached tokio runtime, which means that `Handle::current()` panics in this case. Reverting the commit fixes the issue for now, but this should probably be refactored to use tokio tasks anyway...

Author: Turbo87

src/bin/crates-admin/render_readmes.rs

@@ -125,13 +125,17 @@ pub async fn run(opts: Opts) -> anyhow::Result<()> {
                     println!("[{}-{}] Rendering README...", krate_name, version.num);
                     let readme = get_readme(&storage, &client, &version, &krate_name)?;
                     if !readme.is_empty() {
-                        Handle::current()
-                            .block_on(storage.upload_readme(
-                                &krate_name,
-                                &version.num,
-                                readme.into(),
-                            ))
-                            .context("Failed to upload rendered README file to S3")?;
+                        let rt = tokio::runtime::Builder::new_current_thread()
+                            .enable_all()
+                            .build()
+                            .context("Failed to initialize tokio runtime")?;
+
+                        rt.block_on(storage.upload_readme(
+                            &krate_name,
+                            &version.num,
+                            readme.into(),
+                        ))
+                        .context("Failed to upload rendered README file to S3")?;
                     }
 
                     Ok(())