Update dependency tiktoken to ^0.9.0 (#2054)

Co-authored-by: renovate[bot] <29139614+renovate[bot]@users.noreply.github.com>

Author: renovate[bot]

poetry.lock

@@ -85,7 +85,7 @@ onnxruntime = "1.20.1"
 openai = "^1.55.3"
 litellm = "1.61.4"
 langchain = "^0.3.11"
-tiktoken = "^0.8.0"
+tiktoken = "^0.9.0"
 llama-index = "^0.12.6"
 llama-index-llms-openai = "^0.3.12"
 llama-index-agent-openai = "^0.4.1"