chore(deps): bump tiktoken from 0.8.0 to 0.9.0

Bumps [tiktoken](https://github.com/openai/tiktoken) from 0.8.0 to 0.9.0.
- [Release notes](https://github.com/openai/tiktoken/releases)
- [Changelog](https://github.com/openai/tiktoken/blob/main/CHANGELOG.md)
- [Commits](openai/tiktoken@0.8.0...0.9.0)

---
updated-dependencies:
- dependency-name: tiktoken
  dependency-version: 0.9.0
  dependency-type: direct:production
  update-type: version-update:semver-minor
...

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

Author: dependabot[bot]

requirements/base.txt

@@ -13,4 +13,4 @@ pydantic==2.10.4
 pydantic-settings==2.7.1
 python-dotenv==1.1.0
 pypdf==5.2.0
-tiktoken==0.8.0
+tiktoken==0.9.0