Is your feature request related to a problem? Please describe.

Langchain is currently a core dependency of the RTDIP package. It is a pretty big library and I imagine that langchain is being used for only a niche area of the RTDIP package.

Describe the solution you'd like

Rather than requiring it as a core dependency, perhaps it could be an optional dependency that is only installed if required? This would reduce the number of library installs that are required when using the package, avoiding unnecessary installs for most users.