Adjust Licence to GPL2+

[da2ce7]

Hello @nicklan

We are planing to use your crate using this in our AGPL3 program, technically this is a license violation, because you have selected GPL2, but we use the version 3 of the licenses.

If possible could you update the crates license to be GPL2+, this allows the use of this crate in GPL2, 3, and later versions.

Kind Regards,
Cameron.