langchain

630ae24b - implement get_num_tokens to use google's count_tokens function (#10565)

implement get_num_tokens to use google's count_tokens function (#10565) can get the correct token count instead of using gpt-2 model **Description:** Implement get_num_tokens within VertexLLM to use google's count_tokens function. (https://cloud.google.com/vertex-ai/docs/generative-ai/get-token-count). So we don't need to download gpt-2 model from huggingface, also when we do the mapreduce chain we can get correct token count. **Tag maintainer:** @lkuligin **Twitter handle:** My twitter: @abehsu1992626 --------- Co-authored-by: Bagatur <baskaryan@gmail.com>