Compatibility with MSYS2

[heojaehun]

Hello!

Many thanks for putting together such a fantastic package.
I'm happy to say that I'm using iup-go, thanks to your efforts.

I just wanted to share something I recently discovered with everyone.
If you want to use iup-go on Windows, just make sure you're using MSYS2 20240507 or a lower version.

Just a heads-up: If you use a MSYS2 version after July 27, 2024, it won't build because of a type issue with the functions declared in the windows.h file.

You can manually modify the file and use it, but unless you really need the latest MSYS2, you should use the 20240507 version.

Thanks again to @gen2brain and all the other contributors for another great IUP-GO.