add langchain install

[sfc-gh-rroy]

Description

Please include a summary of the changes and the related issue that can be
included in the release announcement. Please also include relevant motivation
and context.

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Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to
  not work as expected)
• New Tests
• This change includes re-generated golden test results
• This change requires a documentation update

---

Important

Add langchain-openai to test setup and update Python version to 3.9.0 in multiple pyproject.toml files.

• Dependencies:
  • Add langchain-openai to test environment in Makefile.
  • Update langchain-core to >=0.3.0 in src/providers/langchain/pyproject.toml.
  • Update nemoguardrails to >=0.11 in src/apps/nemo/pyproject.toml.
• Python Version:
  • Update minimum Python version to ^3.9.0 in src/apps/langchain/pyproject.toml, src/apps/llamaindex/pyproject.toml, src/apps/nemo/pyproject.toml, src/providers/langchain/pyproject.toml, and src/providers/openai/pyproject.toml.

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