Cranking the major version mattered back when we were making major functional improvements or
incompatible change. OpenSSH 2.0 brought in SSH protocol version 2 support for the first time.
OpenSSH 3.0 changed some defaults in a way that could affect some users.
Nowadays OpenSSH is a mature product, so we just increment the version when we do a timed
(~every 6 months) release.