import the debian/copyright file from debian

Co-Authored-By: Angus Lees <[email protected]>
Co-Authored-By: Fabian Grünbichler <[email protected]>
Co-Authored-By: Hiroaki Nakamura <[email protected]>
Co-Authored-By: Jordan Justen <[email protected]>
Co-Authored-By: Luca Bruno <[email protected]>
Co-Authored-By: Sylvestre Ledru <[email protected]>
Co-Authored-By: Ximin Luo <[email protected]>

Author: 8 people