adjust signature to crate specification

src/main.rs

@@ -13,9 +13,11 @@ pub const Q: u32 = 100;
 mod cell;
 use cell::*;
 
+use reqwest::Error;
 use std::{thread, time::Duration};
 
-fn main() {
+#[tokio::main]
+async fn main() -> Result<(), Error> {
     // Initialize grid randomly
     let mut grid = init_grid(None);
 
@@ -27,4 +29,6 @@ fn main() {
         update_grid(&mut grid);
         thread::sleep(Duration::from_millis(1000 / (FPS as u64)));
     }
+
+    // Ok(())
 }