Incorrect namespace in chatbot to retrieve memories

[sethi-ishmeet]

When saving memory, the namespace used is namespace=("memories", "{user_id}", function_name)

However, in chatbot when retrieving memories, the namespace used is: namespace = (configurable.user_id,)

Due to this mismatch, the chatbot is not retrieving correct memories.

[sethi-ishmeet]

Created a PR with a fix.