Use tokio::time::sleep instead of blocking threads

Great explanation by @LarsWirzenius on the why

> Async code in Rust runs in one or more threads. Usually there's a
small number of threads that are multiplexed between different async
functions. The async executor chooses what threads to use and which
thread runs which async code. If the async code takes a long time, such
as by calling std::thread::sleep, the whole thread stops doing anything
else, and then no other async code runs in that thread, either.

Cargo.lock

@@ -4006,6 +4006,7 @@ dependencies = [
  "tauri-plugin-shell",
  "tauri-plugin-window-state",
  "thiserror",
+ "tokio",
  "ts-rs",
 ]