Copyright for clblast source package in Bullseye

Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
Upstream-Name: CLBlast
Source: https://cnugteren.github.io/clblast/clblast.html

Files: *
Copyright: 2015-2020 Cedric Nugteren and CLBlast contributors
License: Apache-2.0

Files: debian/*
Copyright: 2020 Gard Spreemann 
License: Apache-2.0

License: Apache-2.0
 The project is licensed under Apache Version 2.0.
 .
 On Debian systems, the full text of the license can be found in the file
 "/usr/share/common-licenses/Apache-2.0".