Pin setup-rye in GitHub workflows

[mcgrew-oai]

Why

PR #3083 was merged into next by mistake. This PR replays the same workflow changes against the default branch, main.

Changes

Replace manual Rye installation in GitHub Actions workflows with eifinger/setup-rye pinned to a full commit SHA.

This updates the Rye setup steps in:

• .github/workflows/ci.yml
• .github/workflows/create-releases.yml
• .github/workflows/detect-breaking-changes.yml
• .github/workflows/publish-pypi.yml

Changes included:

• replace curl -sSf https://rye.astral.sh/get | bash bootstrap steps
• pin eifinger/setup-rye to c694239a43768373e87d0103d7f547027a23f3c8
• keep Rye explicitly pinned to 0.44.0
• enable action-level caching
• preserve existing workflow conditions
• set working-directory: openai-python for the nested checkout in detect-breaking-changes.yml

Verification

• confirmed the cherry-pick applied cleanly on top of main
• confirmed the workflow diffs match the prior merged change
• confirmed the updated workflow files contain the pinned setup-rye references and expected working-directory entries

Supersedes #3083 for the main branch target.