Fix evaluation workflow

[pamelafox]

Purpose

This pull request includes changes to the GitHub Actions workflow to correctly identify and use the pull request branch name when committing and pushing evaluation results. The most important changes involve adding a step to get the PR branch name and modifying the branch checkout and push commands.

Improvements to workflow:

• .github/workflows/evaluate.yaml: Added a step to get the PR branch name using actions/github-script@v7 and modified the branch checkout command to create a temporary branch.
• .github/workflows/evaluate.yaml: Updated the push command to use the PR branch name instead of the default branch.

Does this introduce a breaking change?

When developers merge from main and run the server, azd up, or azd deploy, will this produce an error? If you're not sure, try it out on an old environment.

[ ] Yes
[ ] No

Type of change

[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ ] Documentation content changes
[ ] Other... Please describe:

Code quality checklist

See CONTRIBUTING.md for more details.

• [ ] The current tests all pass (python -m pytest).
• [ ] I added tests that prove my fix is effective or that my feature works
• [ ] I ran python -m pytest --cov to verify 100% coverage of added lines
• [ ] I ran python -m mypy to check for type errors
• [ ] I either used the pre-commit hooks or ran ruff manually on my code.

[pamelafox]

/evaluate

[github-actions[bot]]

Starting evaluation! Check the Actions tab for progress, or wait for a comment with the results.

[github-actions[bot]]

Evaluation results

metric	stat	baseline	pr126
gpt_groundedness	pass_rate	1.0	1.0
↑	mean_rating	5.0	5.0
gpt_relevance	pass_rate	1.0	1.0
↑	mean_rating	5.0	5.0
answer_length	mean	1017.6	1011.4
latency	mean	2.56	2.62
citations_matched	mean	0.73	0.73

Check the workflow run for more details.