Bump langchain-core from 0.1.15 to 0.1.16

Bumps [langchain-core](https://github.com/langchain-ai/langchain) from 0.1.15 to 0.1.16.
- [Release notes](https://github.com/langchain-ai/langchain/releases)
- [Commits](https://github.com/langchain-ai/langchain/commits)

---
updated-dependencies:
- dependency-name: langchain-core
  dependency-type: direct:production
  update-type: version-update:semver-patch
...

Signed-off-by: dependabot[bot] <[email protected]>