[5.5] Worker: Allow to set sleep time less than 1 seconds (#22246)

* Worker: Allow to set sleep time less than 1 seconds

* Fixed code style

* Update Worker.php

Author: Alexandr Hacicheant

src/Illuminate/Queue/Worker.php

@@ -593,12 +593,12 @@ public function kill($status = 0)
     /**
      * Sleep the script for a given number of seconds.
      *
-     * @param  int   $seconds
+     * @param  int|float   $seconds
      * @return void
      */
     public function sleep($seconds)
     {
-        sleep($seconds);
+        usleep($seconds * 1000000);
     }
 
     /**