zmupdate.pl applied every zm_update-*.sql at or above the database's
version, with no upper bound. Migration files from a newer release left
in the update directory, after a downgrade or with a newer build's files
installed over an older one, were applied to a schema they were not
written for. Installing a 1.38 build over a 1.39 one ran the 1.39.0 to
1.39.5 migrations against the 1.38 database before one failed.
Skip, and say so, any migration newer than ZM_VERSION.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>