Bump tiktoken from 0.7.0 to 0.8.0

Bumps [tiktoken](https://github.com/openai/tiktoken) from 0.7.0 to 0.8.0.
- [Release notes](https://github.com/openai/tiktoken/releases)
- [Changelog](https://github.com/openai/tiktoken/blob/main/CHANGELOG.md)
- [Commits](openai/tiktoken@0.7.0...0.8.0)

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

Signed-off-by: dependabot[bot] <[email protected]>

Author: dependabot[bot]

requirements/requirements.txt

@@ -130,7 +130,7 @@ sniffio==1.3.1
     #   openai
 tenacity==8.4.2
     # via langchain-core
-tiktoken==0.7.0
+tiktoken==0.8.0
     # via
     #   -r requirements/requirements.in
     #   langchain-openai