A sleep in one request handler stops other handlers from serving
As mentioned [in this thread on Reddit](https://www.reddit.com/r/nim/comments/gyvzdy/prologue_fullstack_web_framework_written_in_nim/fxbl201/), putting a sleep in one async handler stops another from handling a request. Example code:

```
import os
import prologue
import prologue/middlewares/middlewares


proc home*(ctx: Context) {.async.} =
  resp "<h1>Home</h1>"

proc sleepPage*(ctx: Context) {.async.} =
  sleep(10000)
  resp "<h1>Sleep!</h1>"


let settings = newSettings(appName = "MyApp")
var app = newApp(settings = settings, middlewares = @[debugRequestMiddleware()])
app.addRoute("/", home, @[HttpGet, HttpPost])
app.addRoute("/home", home, HttpGet)
app.addRoute("/sleep", sleepPage, HttpGet)
app.run()
```

If you browse to the `/sleep` page, and then the `/` home page, the loading of the home page will block. If the code is built with threads enabled, the blocking behavior is not present.