[patch] [engg]: Update GitHub issues triage action with models token

[juan-arias]

Proposed changes

Describe what this PR is trying to do.

Type of change

• Feature work
• Bug fix
• Documentation
• Engineering change
• Test
• Logging/Telemetry

Risk

• High – Errors could cause MAJOR regression of many scenarios. (Example: new large features or high level infrastructure changes)
• Medium – Errors could cause regression of 1 or more scenarios. (Example: somewhat complex bug fixes, small new features)
• Small – No issues are expected. (Example: Very small bug fixes, string changes, or configuration settings changes)

Additional information

This pull request makes a small but important update to the GitHub Actions workflow for AI-powered issue auto-replies. The change switches the authentication token used by the workflow to a more specific token for Copilot models.

• Workflow authentication: Changed the GH_TOKEN environment variable in .github/workflows/ai-issues-auto-reply.yml to use the GH_COPILOT_PAT_MODELS secret instead of the default GITHUB_TOKEN, improving security and aligning with best practices for token usage.

[Copilot]

Pull request overview

Updates the GitHub Actions workflow that auto-replies to newly opened GitHub issues using GitHub Models, changing which token is used to authenticate to the Models API.

Changes:

• Switch GH_TOKEN from the default GITHUB_TOKEN to the GH_COPILOT_PAT_MODELS secret for the Models API call.