Rewrite Rust benchmarks (#5)

Author: purplesyringa

rust_async_std/Cargo.lock

@@ -5,4 +5,3 @@ edition = "2021"
 
 [dependencies]
 async-std = { version = "1.13.0", features = ["attributes"] }
-futures = "0.3.31"

rust_async_std/Cargo.toml

@@ -1,17 +1,18 @@
 use std::env;
 use async_std::task;
-use futures::future::join_all;
 use std::time::Duration;
 
 #[async_std::main]
 async fn main() {
     let args: Vec<String> = env::args().collect();
     let num_tasks = args[1].parse::<usize>().unwrap();
-    
+
     let mut tasks = Vec::new();
     for _ in 0..num_tasks {
-        tasks.push(task::sleep(Duration::from_secs(10)));
+        tasks.push(task::spawn(task::sleep(Duration::from_secs(10))));
     }
 
-    join_all(tasks).await;
+    for task in tasks {
+        task.await;
+    }
 }