Upgrade REST API Spec from Swagger 2.0.0 to OAS 3.1.x

[Adam Setch]

Current Behavior

Currently the Dependency Track REST API Specification uses Swagger 2.0.0

Proposed Behavior

Upgrade to OpenAPI Spec (OAS) 3.1.x

Checklist

• I have read and understand the contributing guidelines
• I have checked the existing issues for whether this enhancement was already requested

[Niklas]

Duplicate of #840.

[Adam Setch]

Duplicate of #840.

D'oh! I swear I did a search before creating 😅 Thanks @nscuro