stunnel-exception is not yet in the license exception list v3.21
published at https://spdx.org/licenses/exceptions-index.html, but it has
been merged upstream in github.com/spdx/license-list-XML#2074 and will
appear in a future release.
Additionally switch to %autorelease and %autochangelog.
Signed-off-by: Clemens Lang <cllang@redhat.com>
