GitHub Actions: macOS 13 runner image is closing down

[QJKX]

On December 4th.

https://github.blog/changelog/2025-09-19-github-actions-macos-13-runner-image-is-closing-down/

#3436

[ann0see]

Thanks for notifying us. We did indeed get an E-Mail that the runner is soon being disabled. The question is how we handle the legacy build. Qt 5 is still needed - there are some bad bugs in Qt6 (e.g. broken accessability).