`Dataset.inseries` is missing `optional` in the diagram in DCAT-AP HVD 3.0.0

`Dataset.inseries` is missing `optional` in the [diagram](https://semiceu.github.io/DCAT-AP/releases/3.0.0-hvd/#application-profile-diagram) in DCAT-AP HVD 3.0.0

<img width="536" height="190" alt="Image" src="https://github.com/user-attachments/assets/777edc3f-5498-44aa-847d-ecfbd81862e5" />