chore(deps): bump tiktoken from 1.0.17 to 1.0.20

Bumps [tiktoken](https://github.com/dqbd/tiktoken) from 1.0.17 to 1.0.20.
- [Release notes](https://github.com/dqbd/tiktoken/releases)
- [Changelog](https://github.com/dqbd/tiktoken/blob/main/CHANGELOG.md)
- [Commits](https://github.com/dqbd/tiktoken/compare/tiktoken@1.0.17...tiktoken@1.0.20)

---
updated-dependencies:
- dependency-name: tiktoken
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <support@github.com>