Bump openai from 0.27.8 to 0.28.0

Bumps [openai](https://github.com/openai/openai-python) from 0.27.8 to 0.28.0.
- [Release notes](https://github.com/openai/openai-python/releases)
- [Commits](openai/openai-python@v0.27.8...v0.28.0)

---
updated-dependencies:
- dependency-name: openai
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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