Add Trivy scanner workflow

[yevh]

Changes

Trivy is added. Trivy is a lightweight image scanning tool that may discover vulnerabilities and misconfigurations. Actions pinned to specific commit hashes:

• trivy-action@5681af892cd0f4997658e2bacc62bd0a894cf564 #v0.27.0
• checkout@d632683dd7b4114ad314bca15554477dd762a938 #v4.2.0
• codeql-action/init@5618c9fc1e675841ca52c1c6b1304f5255a905a0 #v2.19.0
• setup-dotnet@6bd8b7f7774af54e05809fcc5431931b3eb1ddee #v4.0.1

Types of changes

What types of changes does your code introduce?

• Bugfix (a non-breaking change that fixes an issue)
• New feature (a non-breaking change that adds functionality)
• Breaking change (a change that causes existing functionality not to work as expected)
• Optimization
• Refactoring
• Documentation update
• Build-related changes
• Other: Image scanning is added.

Testing

Requires testing

• Yes
• No

If yes, did you write tests?

• Yes
• No

Documentation

Requires documentation update

• Yes
• No

Requires explanation in Release Notes

• Yes
• No

[github-advanced-security]

This pull request sets up GitHub code scanning for this repository. Once the scans have completed and the checks have passed, the analysis results for this pull request branch will appear on this overview. Once you merge this pull request, the 'Security' tab will show more code scanning analysis results (for example, for the default branch). Depending on your configuration and choice of analysis tool, future pull requests will be annotated with code scanning analysis results. For more information about GitHub code scanning, check out the documentation.

[rubo]

Major changes:

• Revised Docker image tag name
• Switched to the latest Ubuntu as 20.04 is too old
• Updated aquasecurity/trivy-action to v0.28.0