package/kodi-pvr-vdr-vnsi: bump version to 8.2.1-Matrix

package/kodi-pvr-vdr-vnsi: bump version to 8.2.1-Matrix

Switch dependency to kodi after upstream removed the dependency to
kodi-platform:
https://github.com/kodi-pvr/pvr.vdr.vnsi/commit/d8af242ba923590330c65fded9034c1ac9b6157c
https://github.com/kodi-pvr/pvr.vdr.vnsi/commit/49cc728f18bbe8df1d1779eb5e42e060fa9f78ed

Added dependency to gcc >= 7 due to c++17 code added by
https://github.com/kodi-pvr/pvr.vdr.vnsi/commit/8a3f3c8fe378a4aae4ac381db45d0ce980f44761

Switch license file to LICENSE.md.

Signed-off-by: Bernd Kuhls <bernd.kuhls@t-online.de>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>