fix: Fixed issue labels adoption

[stevehipwell]

Resolves #2089

---

Before the change?

• You couldn't use github_issue_labels to manage an existing label

After the change?

• You can use github_issue_labels to manage an existing label

Pull request checklist

• [x] Tests for the changes have been added (for bug fixes / features)
• [x] Docs have been reviewed and added / updated if needed (for bug fixes / features)

Does this introduce a breaking change?

Please see our docs on breaking changes to help!

• [ ] Yes
• [x] No

---