www/kanboard: update to 1.2.43

ChangeLog: https://kanboard.org/releases/kanboard/v1.2.43.html

• fix: verify the session hasn't expired before returning data (CVE-2024-55603)
• fix: avoid PHP 8.4 deprecation notices in third-party libraries
• fix: avoid Composer warnings regarding PSR compatibility
• feat(locale): add missing Brazilian Portuguese translations
• ci: run GitHub Actions tests with ubuntu-24.04
• chore: don't export-ignore the ChangeLog
• build(deps): bump symfony/service-contracts from 2.5.3 to 2.5.4
• build(deps): bump symfony/event-dispatcher-contracts from 2.5.3 to 2.5.4
• build(deps): bump symfony/deprecation-contracts from 2.5.3 to 2.5.4
• build(deps): bump alpine from 3.20 to 3.21

CVE-2024-55603:

• Base Score: 6.5 MEDIUM
• Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:N

Security: CVE-2024-55603