Adjust the Trivy scanning workflow to upload artifacts

[hansinikarunarathne]

Pull Request Template for Kubeflow manifests Issues

✏️ A brief description of the changes

I added the new step to upload Trivy results artifacts.
By default, GitHub Actions artifacts are retained for 90 days before they are automatically deleted. However, you can adjust the retention period as needed. For more information, refer to the GitHub documentation on configuring the retention period for GitHub Actions artifacts and logs.

✅ Contributor checklist

• Make sure you have tested with kustomize. See Installation Prerequisites
• All the commits have been signed-off (To pass the DCO check)
• Submit the Contributor License Agreements (To pass the cla/google check)

---

You can join the CNCF Slack and access our meetings at the Kubeflow Community website. Our channel on the CNCF Slack is here #kubeflow-platform.

[tarilabs]

/lgtm

thank you!

[juliusvonkohout]

/approve

[google-oss-prow]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: juliusvonkohout

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Needs approval from an approver in each of these files:

• OWNERS [juliusvonkohout]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment