Upgrade to GitHub API 2.x

[jonesbusy]

Update GitHub API to 2.0-alpha-3

Testing done

Automated tests

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[jonesbusy]

Would you agree to now depends on 2.0-alpha-3 so that we can progress and other feature like main branch only fork or SSH public keys retrieval.

If think the risk is low, we are only using some subset of GitHub API features.

[jonesbusy]

#504
#104