fix: enforce correct type for security-severity in sarif output

[thisislawatts]

Pull Request Submission

Please check the boxes once done.

The pull request must:

• Reviewer Documentation
  • follow CONTRIBUTING rules
  • be accompanied by a detailed description of the changes
  • contain a risk assessment of the change (Low | Medium | High) with regards to breaking existing functionality. A change e.g. of an underlying language plugin can completely break the functionality for that language, but appearing as only a version change in the dependencies.
  • highlight breaking API if applicable
  • contain a link to the automatic tests that cover the updated functionality.
  • contain testing instructions in case that the reviewer wants to manual verify as well, to add to the manual testing done by the author.
  • link to the link to the PR for the User-facing documentation
• User facing Documentation
  • update any relevant documentation in gitbook by submitting a gitbook PR, and including the PR link here
  • ensure that the message of the final single commit is descriptive and prefixed with either feat: or fix: , others might be used in rare occasions as well, if there is no need to document the changes in the release notes. The changes or fixes should be described in detail in the commit message for the changelog & release notes.
• Testing
  • Changes, removals and additions to functionality must be covered by acceptance / integration tests or smoke tests - either already existing ones, or new ones, created by the author of the PR.

Pull Request Review

All pull requests must undergo a thorough review process before being merged.
The review process of the code PR should include code review, testing, and any necessary feedback or revisions.
Pull request reviews of functionality developed in other teams only review the given documentation and test reports.

Manual testing will not be performed by the reviewing team, and is the responsibility of the author of the PR.

For Node projects: It’s important to make sure changes in package.json are also affecting package-lock.json correctly.

If a dependency is not necessary, don’t add it.

When adding a new package as a dependency, make sure that the change is absolutely necessary. We would like to refrain from adding new dependencies when possible.
Documentation PRs in gitbook are reviewed by Snyk's content team. They will also advise on the best phrasing and structuring if needed.

Pull Request Approval

Once a pull request has been reviewed and all necessary revisions have been made, it is approved for merging into
the main codebase. The merging of the code PR is performed by the code owners, the merging of the documentation PR
by our content writers.

What does this PR do?

Addresses defect in recently shipped security-severity property.

properties.security-severity
(Recommended only for security rules) If you include a value for this field, results for the rule are treated as security results. A string representing a score that indicates the level of severity, between 0.0 and 10.0, for security queries (@tags includes security). This, with the properties.precision property, determines whether the results are displayed by default on GitHub so that the results with the highest security-severity, and highest precision are shown first. Code scanning translates numerical scores as follows: over 9.0 is critical, 7.0 to 8.9 is high, 4.0 to 6.9 is medium and 3.9 or less is low.
Reference: https://docs.github.com/en/code-security/code-scanning/integrating-with-code-scanning/sarif-support-for-code-scanning#reportingdescriptor-object

Thanks to @pgrabowski for reporting this ✨
#5014 (comment)

[jmqd]

I believe if vuln.cvssScore is null, this pushes "undefined" to the property bag.

I would suggest adding a null testcase and verifying.

[AngellusMortis]

Can confirm. Github Code Scanning is now rejecting sarif files from Snyk CLI.