Update to Node 18

What does this MR do?

This MR updates the security report schema project to use Node 18. The previous version (14) is no longer supported, and as a result, insecure.

What are the relevant issue numbers?

This is in preparation for the MR that implements Add support for CVSS vectors in the security re... (gitlab-org/gitlab#422031 - closed).

Checklist

• Ensure changes can be built upon without requiring a breaking change, see Building for Extensibility.
• Review and add/update tests for this feature/bug.
• Add an entry to the CHANGELOG if required, with the appropriate version. See Classifying Changes.
  • Not required because it does not change the schema.
• Assign the MR to the appropriate person/people for review.