Fix concurrency issue in gemini-cli workflow

[galz10]

This PR addresses a concurrency issue in the gemini-cli workflow that could cause multiple workflow to be canceled when comments from the same branch/repo triggered the gemini-cli workflow.

The previous concurrency key was too broad, using github.head_ref or github.ref, which are not always relevant in the context of an issue_comment event.

The fix simplifies the concurrency group to be solely based on the issue number:

concurrency:
  group: '${{ github.workflow }}-${{ github.event.issue.number }}'
  cancel-in-progress: true

This ensures that only one instance of the workflow runs per issue at any given time, correctly canceling any in-progress runs when a new comment is created or an existing one is edited.

[gemini-cli]

📋 Review Summary

This PR provides a targeted and effective fix for a concurrency issue within the gemini-cli GitHub Actions workflow. By refining the concurrency group key, the change ensures that workflow runs are correctly scoped to individual issues, preventing premature cancellations.

🔍 General Feedback

The proposed change is a clear improvement. Simplifying the concurrency key not only resolves the immediate issue but also enhances the maintainability and predictability of the workflow. The change is well-documented in the PR body, making the purpose clear.

🎯 Specific Feedback

No specific issues identified in this review.

✅ Highlights

• Effective Fix: The change directly and efficiently addresses the identified concurrency problem.
• Improved Readability: The new concurrency key is simpler and easier to understand, which is a great enhancement for maintainability.
• Good Practice: This is a good example of correctly scoping concurrency in a GitHub Actions workflow to the triggering event.