IssueSchema description can be null

**Description** - Node.js version: 24.10.0 - Gitbeaker version: 43.8.0 - Gitbeaker release (cli, rest, core, requester-utils): rest - OS & version: Ubuntu 24 - Gitlab self hosted version: 18.3.1 The `description` of an issue retrieved with either `Issues.all` or `Issues.show` can yield `null`: <img width="340" height="175" alt="Image" src="https://github.com/user-attachments/assets/9a8d4662-9d40-4ef7-91f1-453b5dc4efd1" /> In one of our projects, 25 of 2208 issues have their description `null`. **Steps to reproduce** One way to get a null-description is via an epic: - Create an issue from an epic via the inline feature to add a child element - This issue will have its description then as `null` <img width="938" height="261" alt="Image" src="https://github.com/user-attachments/assets/7941e80e-7e33-4875-921c-d85dab6c8fec" /> **Expected behaviour** - The type for `description` should be `string | null` **Actual behaviour** - The type for `description` is `string` **Possible fixes** - Please just extend the type **Checklist** - [x] I have checked that this is not a duplicate issue. - [x] I have read the documentation.