Pin setup-rye in GitHub workflows

[mcgrew-oai]

Changes being requested

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

Additional context & links

Verified locally that:

• there are no remaining manual Rye install steps in .github/workflows
• there are no remaining RYE_VERSION / RYE_INSTALL_OPTION env blocks for Rye setup
• the edited workflow files parse as YAML

Upstream references used for the pin/version:

• eifinger/setup-rye latest release: v4.2.9
• release commit: c694239a43768373e87d0103d7f547027a23f3c8
• astral-sh/rye latest release: 0.44.0