databases/mantis: Update to 2.26.0

re: https://mantisbt.org/bugs/changelog_page.php?version_id=360

https://mantisbt.org/bugs/changelog_page.php?version_id=370

Fixes two CVEs

PR: 276022
Security: CVE-2023-29197 CVE-2023-44394
(cherry picked from commit 3cf4de18e8b4bc8dfbdbfbde68ad9709b64cdd21)