ci: upgrade mikepenz/action-junit-report v5 to v6 (#20042)
[upgrade mikepenz/action-junit-report to v6 to resolve Node.js
deprecation](https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/)
"Node.js deprecation warnings (e.g., mikepenz/action-junit-report@v5
requiring Node.js 20) no longer appear in specific Actions runs, such as
this job, following the upgrade to v6."
https://github.com/dpy013/nvda/actions/runs/25235122899/job/74002155719?spm=5176.28103460.0.0.96a02988qH35o5
Signed-off-by: dpy013 <26911141+dpy013@users.noreply.github.com>
