Add daily vulnerability scan

[R-HNF]

Description

I have updated three files for daily vulnerability scan.

1. daily-vul-scan.yml
2. README.md
3. trivy-results.tpl

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1. daily-vul-scan.yml

Add daily vulnerability scan workflow daily-vul-scan.yml using trivy-action created by the official Trivy team.

This is the result of a test run.

• https://github.com/R-HNF/gatling-operator/actions/runs/6529806592

2. README.md

Add a badge to README.md to display the workflow results on the main branch.

Sample:

The result is marked as failing due to vulnerabilities. ref. https://github.com/R-HNF/gatling-operator/tree/add_daily-vul-scan

3. trivy-results.tpl

Add a template trivy-results.tpl for writing out Trivy results to an issue.

This is the sample of a test run.

• https://github.com/R-HNF/gatling-operator/issues/3

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Checklist

Please check if applicable

• [x] Tests have been added (if applicable, ie. when operator codes are added or modified)
• [x] Relevant docs have been added or modified (if applicable, ie. when new features are added or current features are modified)

Relevant issue #45