OpenAPI spec. wrong for PUT /api/v1/project return

### Current Behavior

While creating a project using PUT /api/v1/project with a client generated from OpenAPI spec. (here nswag), without an existing SBOM, `lastBomImport` is not returned. (omitted when null)

Return spec. for `Project` state `lastBomImport` is a required and present even if null.

DT: v4.13.2

### Proposed Behavior

PUT /api/v1/project return `Project` specification should set `lastBomImport` as omitted when null or ignored when not set. (or set to null)

### Checklist

- [x] I have read and understand the [contributing guidelines](https://github.com/DependencyTrack/dependency-track/blob/master/CONTRIBUTING.md#filing-issues)
- [x] I have checked the [existing issues](https://github.com/DependencyTrack/dependency-track/issues) for whether this enhancement was already requested