Fix auto-assign workflow for pull requests from forks

[Copilot]

The auto-assign workflow fails on fork PRs with Resource not accessible by integration because GITHUB_TOKEN lacks write permissions for security reasons.

Changes

• Added conditional to skip workflow for fork PRs while preserving functionality for same-repo PRs and issues
• Used short-circuit evaluation with explicit null check to prevent runtime errors

jobs:
  run:
    runs-on: ubuntu-latest
    if: github.event_name == 'issues' || (github.event.pull_request != null && github.event.pull_request.head.repo.full_name == github.repository)
    permissions:
      issues: write
      pull-requests: write

The workflow now runs only when GITHUB_TOKEN has sufficient permissions: issues and non-fork pull requests.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Fix the auto-assign issue</issue_title>
<issue_description>The failure is per: https://github.com/Umplify/xunit-dependency-injection/actions/runs/20273296887/job/58220115395?pr=337</issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes Fix the auto-assign issue #338

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[Copilot]

Pull request overview

This PR fixes the auto-assign workflow that was failing on pull requests from forks due to insufficient GITHUB_TOKEN permissions. The workflow now includes a conditional check to skip execution for fork PRs while maintaining functionality for issues and same-repository pull requests.

Key Changes:

• Added conditional logic to prevent workflow execution on fork PRs
• Used explicit null check with short-circuit evaluation for safe property access
• Preserved existing functionality for issues and non-fork PRs