Update tiktoken requirement from ~=0.7.0 to ~=0.8.0

Updates the requirements on [tiktoken](https://github.com/openai/tiktoken) to permit the latest version.
- [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
...

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

requirements.txt

@@ -14,4 +14,4 @@ spacy~=3.7.5
 streamlit~=1.38.0
 pyvis~=0.3.2
 python-dateutil~=2.9.0.post0
-tiktoken~=0.7.0
+tiktoken~=0.8.0