feat: Add support for CVSSv4

[anthonyharrison]

Description

Some of the entries in the NVD now include CVSS v4 data. This should be used as the primary scoring metric if available.

The Common Vulnerability Scoring System (CVSS) provides a way to capture the principal characteristics of a vulnerability and produce a numerical score reflecting its severity. CVSS version 4.0 is the next generation of the Common Vulnerability Scoring System standard; released November 1, 2023. CVSS v4.0 provides increased granularity for Base metrics, a new Supplemental metric group, a different methodology for determining severity and more. For more information regarding CVSS v4.0 please visit https://www.first.org/cvss/v4.0/specification-document.

Why?

Provides an updated metric to assess the severity of a vulnerability