This release is a major release, but the only major thing is all the deprecated sergensio code has been removed. ser2net, the rust and go interfaces have all had that removed for a while and hopefully any other users have removed it. sergensio, in the end, just didn't make any sense.
There are also some minor bug fixes, some documentation improvements, some minor improvements, and a bug fix around ax25 where it was reporting the close of the last channel too soon.