It is not strictly required to remove packaging for an older distro, could be people still using it in internal network and still be fine with it. Of course, if @sergey-safarov wants to remove it, that's fine, he spends time for packaging and can consider it's not worth doing it.
On the other hand, the commit message does not follow the guidelines:
* https://github.com/kamailio/kamailio/blob/master/.github/CONTRIBUTING.md#com...
So the PR cannot be merged as it is from web interface.