Copyright for castxml source package in Sid

Format: https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/
Upstream-Name: CastXML
Upstream-Contact: castxml@public.kitware.com
Source: https://github.com/CastXML/CastXML

Files: *
Copyright: 2013-2021 Kitware, Inc.
License: Apache-2.0
 On Debian systems, the full text of the Apache
 License version 2.0 can be found in the file
 /usr/share/common-licenses/Apache-2.0.