chore(deps): bump langchain-core in /packages/sample-app

Bumps [langchain-core](https://github.com/langchain-ai/langchain) from 0.3.74 to 0.3.80. - [Release notes](https://github.com/langchain-ai/langchain/releases) - [Commits](langchain-ai/langchain@langchain-core==0.3.74...langchain-core==0.3.80) --- updated-dependencies: - dependency-name: langchain-core dependency-version: 0.3.80 dependency-type: indirect ... Signed-off-by: dependabot[bot] <support@github.com>

Author: dependabot[bot]