chore!: refine windows platform configuration

[cavivie]

Closes 75.

[cavivie]

I don't understand why the .dll ext needs to be removed here?

[ssrlive]

It can be automatically added by the LoadLibraryExW function.

[cavivie]

In this case, I prefer to say wintun_path here is wintun_file to make it clearer that wintun is just a filename or a filename with an extension, because wintun looks too much like a path due to the function name is called wintun_path, which will lead users to use wintun path(directory). What do you think?