switch to simpler single threaded tokio runtime

Less dependencies, yay

src/main.rs

@@ -5,8 +5,7 @@ use rspotify::{prelude::*, scopes, AuthCodeSpotify, Credentials, OAuth};
 const SPOTIFY_WEB_API_ADD_PLAYLIST_MAX_ID_NUM: usize = 100;
 const SPOTIFY_WEB_API_TRACK_FEATURES_MAX_ID_NUM: usize = 100;
 
-#[tokio::main]
-async fn main() {
+async fn build_new_playlist() {
     let args: Vec<String> = std::env::args().collect();
     if args.len() != 4 {
         eprintln!("usage: {} PLAYLIST_TITLE MIN_TEMPO MAX_TEMPO", args[0]);
@@ -90,3 +89,13 @@ async fn main() {
             .unwrap();
     }
 }
+
+fn main() {
+    tokio::runtime::Builder::new_current_thread()
+        .enable_all()
+        .build()
+        .unwrap()
+        .block_on({
+            build_new_playlist()
+        })
+}