Update commonmarker gem to 0.23.9 (from 0.23.6)

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/121602



Merged-by: Rajendra Kadam <rkadam@gitlab.com>
Approved-by: Costel Maxim <cmaxim@gitlab.com>
Approved-by: Himanshu Kapoor <info@fleon.org>
Approved-by: Savas Vedova <svedova@gitlab.com>
Approved-by: Sam Figueroa <sfigueroa@gitlab.com>
Approved-by: Rajendra Kadam <rkadam@gitlab.com>
Co-authored-by: Brett Walker <bwalker@gitlab.com>