Fix that debian/changelog is still on 1.12.0 on current master while the latest stable version is on 1.13.x. This is confusing, and it also results in unexpected behavior on debian 13: After enabling the Osmocom nightly repository and asking apt to install osmo-sgsn or osmo-gtphub, it will pick the 1.13.x versions from the debian repository instead of the versions from the Osmocom nightly repository.
