Build(deps): Bump langchain from 0.0.302 to 0.0.308 (#119)

Bumps [langchain](https://github.com/langchain-ai/langchain) from 0.0.302 to 0.0.308.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](langchain-ai/langchain@v0.0.302...v0.0.308)

---
updated-dependencies:
- dependency-name: langchain
  dependency-type: indirect
...

Signed-off-by: dependabot[bot] <[email protected]>
Co-authored-by: dependabot[bot] <49699333+dependabot[bot]@users.noreply.github.com>
Co-authored-by: Janaka Abeywardhana <[email protected]>