ci: use ubuntu-latest for security analysis

[Boshen]

Summary

• Switch the Security Analysis workflow runner from ubuntu-slim to ubuntu-latest.

🤖 Generated with Claude Code

[codspeed-hq]

Merging this PR will degrade performance by 1.11%

⚠️ Different runtime environments detected

Some benchmarks with significant performance changes were compared across different runtime environments,
which may affect the accuracy of the results.

Open the report in CodSpeed to investigate

❌ 1 regressed benchmark
✅ 5 untouched benchmarks

⚠️ Please fix the performance issues or acknowledge them on CodSpeed.

Performance Changes

	Benchmark	BASE	HEAD	Efficiency
❌	oxc[parallel]	137.3 ms	138.9 ms	-1.11%

---

_{Comparing ci/ubuntu-latest (9d03107) with main (4e9486d)}