Add ai_review_label to https://github.com/github/github-mcp-server/blob/main/.github/workflows/ai-issue-assessment.yml

[ai_review_label](https://github.com/github/github-mcp-server/blob/main/.github/workflows/ai-issue-assessment.yml) is missing required `ai_review_label`. Add it and set to `bug`, `enhancement`.
Refer to the docs https://github.com/github/ai-assessment-comment-labeler.
Do not edit other files than `ai-issue-assessment.yml`.