feat: migrate from async-std to tokio

src/dehtml.rs

@@ -382,7 +382,7 @@ mod tests {
         assert_eq!(txt.trim(), "two\nlines");
     }
 
-    #[async_std::test]
+    #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
     async fn test_quote_div() {
         let input = include_str!("../test-data/message/gmx-quote-body.eml");
         let dehtml = dehtml(input).unwrap();