Add CI workflow for updating regression test baselines

[harryswift01]

Summary

This PR will add a GitHub Actions workflow to automate updating regression testing baselines in a consistent CI environment.

Changes

Add regression baseline update workflow:

• Create a new workflow triggered via workflow_dispatch
• Run regression tests with --update-baselines flag in CI
• Configure workflow to run on a stable Ubuntu environment with a fixed Python version

Enable automated commits from CI:

• Grant contents: write permission to allow committing changes
• Add auto-commit step using git-auto-commit-action
• Use Conventional Commit message: test(regression): update baselines
• Configure commits to use github-actions[bot] identity

Improve baseline consistency:

• Ensure baselines are generated in a consistent environment
• Remove dependency on developer local environments
• Reduce noisy diffs caused by path differences

Impact

• Reduces noise in PRs caused by local baseline updates
• Makes regression baseline updates reproducible and consistent
• Simplifies contributor workflow for updating baselines
• Keeps test artifacts aligned with CI environment

[skfegan]

Improving the baseline changes is great. Do we need to update the documentation to explain how to use this new workflow to update the baselines? And explain clearly when updating the baselines is accepted rather than people just doing this every time a regression test fails?

[harryswift01]

Improving the baseline changes is great. Do we need to update the documentation to explain how to use this new workflow to update the baselines? And explain clearly when updating the baselines is accepted rather than people just doing this every time a regression test fails?

Yeah that's a great idea, I'll update the docs to reflect these changes as well.

[jimboid]

This PR looks great and should cut down on the noisey PRs when baseline updates are involved.