Use dual license on Debian

cf https://www.debian.org/doc/packaging-manuals/copyright-format/1.0/

ci/before_deploy.bash

@@ -103,7 +103,36 @@ Source: $homepage
 
 Files: *
 Copyright: $maintainer
+License: Apache-2.0 or MIT
+
 License: Apache-2.0
+ On Debian systems, the complete text of the Apache-2.0 can be found in the
+ file /usr/share/common-licenses/Apache-2.0.
+
+License: MIT
+ Permission is hereby granted, free of charge, to any
+ person obtaining a copy of this software and associated
+ documentation files (the "Software"), to deal in the
+ Software without restriction, including without
+ limitation the rights to use, copy, modify, merge,
+ publish, distribute, sublicense, and/or sell copies of
+ the Software, and to permit persons to whom the Software
+ is furnished to do so, subject to the following
+ conditions:
+ .
+ The above copyright notice and this permission notice
+ shall be included in all copies or substantial portions
+ of the Software.
+ .
+ THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF
+ ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED
+ TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A
+ PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT
+ SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR
+ IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ DEALINGS IN THE SOFTWARE.
 EOF
 
     # completions