License file missing in sdist tarball

[dvzrv]

Hi! While packaging 0.4.1 for Arch Linux I ran into the issue, that the license file of this project is not included in the sdist tarball.
As this software is licensed under the terms of the BSD-3-clause, the license file should be included in all source and binary distributions. This makes impossible for downstreams to package this software legally, if they do not grab the license file from this repository.

Please add the LICENSE file to the sdist tarball! Thanks :)