Fix scan.yaml to use ubuntu-latest OS

[w13915984028]

Problem:

Github refused to run related job as the required Ubuntu OS is EOL.

https://github.com/harvester/network-controller-harvester/actions/runs/13657731201

[Build](https://github.com/harvester/network-controller-harvester/actions/runs/13657731201/job/38181087593)
This is a scheduled Ubuntu 20.04 brownout. Ubuntu 20.04 LTS runner will be removed on 2025-04-01. For more details, see https://github.com/actions/runner-images/issues/11101

Build
GitHub Actions has encountered an internal error when running your job.

Solution:

Use latest OS

Related Issue:
harvester/harvester#4355

Test plan:

All PRs should run this job successfully.

Scan.yaml runs successfully.
https://github.com/harvester/network-controller-harvester/actions/runs/13657810131

This PR is a cherry-pick from PR #149

[w13915984028]

@mergify backport v1.5

[mergify]

backport v1.5

🟠 Waiting for conditions to match

• merged [📌 backport requirement]

[mingshuoqiu]

LGTM