Bump anthropic from 0.26.0 to 0.28.1

Bumps [anthropic](https://github.com/anthropics/anthropic-sdk-python) from 0.26.0 to 0.28.1.
- [Release notes](https://github.com/anthropics/anthropic-sdk-python/releases)
- [Changelog](https://github.com/anthropics/anthropic-sdk-python/blob/main/CHANGELOG.md)
- [Commits](anthropics/anthropic-sdk-python@v0.26.0...v0.28.1)

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

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