Scan images using Trivy

[P4sca1]

This PR sets up container image scanning using Trivy from Aquasecurity.

• Images will be scanned in the CI workflow.
• Scanning is performed in the containerbuild job after pushing the image to the registry.
• Scan results are available in the workflow log (the comment from github-advanced-security originated from a test to store SARIF outputs in the GitHub security tab and can be ignored).
• When an unfixed critical CVE is found, the pipeline exits with status code 1. Images are already pushed to the registry at this point and can be pulled for further debugging.
• fail-fast was disabled, so that if one containerbuild job from the matrix fails, the other jobs are still executed.

This PR also changes the Python base image version back from 3.12.3 to 3.12. It was pinned to version 3.12.3, because 3.12.4 did not work. The most recent 3.12 version should work again.

Sample workflow log: https://github.com/fkie-cad/Logprep/actions/runs/11236005155/job/31235173514?pr=685

I recommend squashing all commits when merging, because the history is quite messy due to experimenting with the pipeline.

[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.