CI: test against MySQL 9.7 instead of 9.6 by fkmy · Pull Request #300 · trilogy-libraries/trilogy

MySQL 9.7 is the new LTS release (GA on 2026-04-21), superseding the 9.6 innovation release. Refs: https://blogs.oracle.com/mysql/mysql-9-7-lts-is-here-upgrade-and-modernize-on-a-stronger-communit...