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

[JoannaaKL]

ai_review_label 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.