Fix paths on Windows

Actions were not registered correctly on Windows machines.
The `getClassnameFromPathname` method returned the absolute file path in stead of the class name, due to a mismatch of directory separators.

src/ActionManager.php

@@ -22,7 +22,7 @@ class ActionManager
      */
     public function __construct()
     {
-        $this->paths('app/Actions');
+        $this->paths('app'.DIRECTORY_SEPARATOR.'Actions');
         $this->registeredActions = collect();
     }