Add another mirror for Trivy DB in security.yml

[rdimitrov]

Summary

We've been seeing quite often issues with the trivy db rate limits. Hopefully this addresses those.

Also moves from master to a versioned action

Note: let's merge it once there's an existing workflow that does fail (currently rate limits got reset so cannot test it) and confirm that running this one actually worked)

Change Type

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• [x] Bug fix (resolves an issue without affecting existing features)
• [ ] Feature (adds new functionality without breaking changes)
• [ ] Breaking change (may impact existing functionalities or require documentation updates)
• [ ] Documentation (updates or additions to documentation)
• [ ] Refactoring or test improvements (no bug fixes or new functionality)

Testing

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Review Checklist:

• [x] Reviewed my own code for quality and clarity.
• [ ] Added comments to complex or tricky code sections.
• [ ] Updated any affected documentation.
• [ ] Included tests that validate the fix or feature.
• [ ] Checked that related changes are merged.