Mostly just trying to make MyPy happy!

Rather than is_index_populated.

It's defined in the BaseIndex which LocalIndex inherits anyway

Also fixed bug in layer.py where we weren't:
a) Setting the index_name to a default value.
b) Weren't using index_name.

Making pydantic leave me alone and giving the correct index name.

Also made sure it's used properly in layer.py.

fix: pip install error in 03-basic-langchain-agent.ipynb

feat: Incorporating Semantic Topic Splitters into Conversation

Merge branch 'incorporating_topic_splitters' of https://github.com/aurelio-labs/semantic-router into incorporating_topic_splitters

We don't have this function anymore.

Merge branch 'incorporating_topic_splitters' of github.com:aurelio-labs/semantic-router into incorporating_topic_splitters
merge

Rather than Conversation.print_topics().

Prints in nice colours.

And more linting.