ci: update workflow to add upstream remote for fetching branches

[colinaaa]

Summary

When fetch base branch, we should fetch from upstream instead of origin (which is the fork repo).

This would fix CI failure like https://github.com/lynx-family/lynx-stack/actions/runs/14495253377/job/40661745063

Checklist

• Tests updated (or not required).
• Documentation updated (or not required).

[changeset-bot]

⚠️ No Changeset found

Latest commit: 1a0bdad

Merging this PR will not cause a version bump for any packages. If these changes should not result in a new version, you're good to go. If these changes should result in a version bump, you need to add a changeset.

This PR includes no changesets

When changesets are added to this PR, you'll see the packages that this PR includes changesets for and the associated semver types

Click here to learn what changesets are, and how to add one.

Click here if you're a maintainer who wants to add a changeset to this PR

[codecov]

Bundle Report

Bundle size has no change ✅

[codspeed-hq]

CodSpeed Performance Report

Merging #577 will not alter performance

_{Comparing colinaaa:colin/0417/fetch (1a0bdad) with main (f1ca29b)}

Summary

✅ 1 untouched benchmarks