(do not merge) feat: Update langchain to 0.1.20

[devin-ai-integration]

This PR updates langchain to version 0.1.20 (not the latest version, as we encountered compatibility issues with the latest version) and updates the import statements to use the recommended imports from langchain_community.embeddings, langchain_text_splitters, and langchain_core.utils. All unit tests are passing, and all linting and formatting checks pass.

Link to Devin run: https://app.devin.ai/sessions/69141ba57da94653962ece34f74d5728

Requested by: natik@airbyte.io

[devin-ai-integration]

🤖 Devin AI Engineer

Original prompt from natik@airbyte.io:

Received message in Slack channel #dev-devin-ai:

Hey @Devin please make a pull request to `airbytehq/airbyte-python-cdk` that updates `langchain` to it's latest available version.

Then fix all failing unit tests in airbyte_cdk.

Then, take one of the connectors that is writing to vector stores to verify the changes. Let's say `destination-chroma`. Make a separate draft PR where you pin it to the CDK from the branch you make, and see if it works.

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