2147 - Fix notebook bug to make a copy of configs for each agent (#2176)

* try fix groupchat llm_config

* Update agentchat_groupchat_RAG.ipynb

* use better config options

* formatting

---------

Co-authored-by: i <i@jtoy.net>
Co-authored-by: Li Jiang <bnujli@gmail.com>
Co-authored-by: Jason <jtoy@grids.local>
Co-authored-by: Eric Zhu <ekzhu@users.noreply.github.com>