Update syntax to adapt latest hammerspoon

[Eason0210]

Hi @dsanson

Now focusedWindow is a constructor type, in stead of a method.

In hammerspoon manual it is define like this:

 hs.window.focusedWindow() -> window

I tested on macOS 12.3.1 with hammerspoon Version 0.9.91 (6078), and It works well now.