The Artistic Licence covers only modifications to the original source code. Because your file is an addition, not a modification, you are free to license it as you please.
If you're not interested in the provisions of the Artistic License (e.g. people documenting their changes) then it would make sense to use a different license, or alternatively you could just release it into the public domain. But it's your file and you're free to do what you want with it.
