Update conversable agent image

[ekzhu]

Why are these changes needed?

Related issue number

Closes #1936

Checks

• I've included any doc changes needed for https://microsoft.github.io/autogen/. See https://microsoft.github.io/autogen/docs/Contribute#documentation to build and test documentation locally.
• I've added tests (if relevant) corresponding to the changes introduced in this PR.
• I've made sure all auto checks have passed.

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 37.30%. Comparing base (f247b45) to head (80ffad8).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1939   +/-   ##
=======================================
  Coverage   37.30%   37.30%           
=======================================
  Files          64       64           
  Lines        6910     6910           
  Branches     1519     1519           
=======================================
  Hits         2578     2578           
  Misses       4109     4109           
  Partials      223      223           

Flag	Coverage Δ
unittests	37.30% <ø> (ø)

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[sonichi]

Issue for future PR: https://github.com/microsoft/autogen/actions/runs/8219572063/job/22477695984?pr=1939

Warning: Docusaurus found broken anchors!

Please check the pages of your site in the list below, and make sure you don't reference any anchor that does not exist.
Note: it's possible to ignore broken anchors with the 'onBrokenAnchors' Docusaurus configuration, and let the build pass.

Exhaustive list of all broken anchors found:

• Broken anchor on source page path = /autogen/docs/FAQ:
  -> linking to /autogen/docs/installation/Docker#option-1-install-and-run-autogen-in-docker
  -> linking to /autogen/docs/Use-Cases/agent_chat#cache
• Broken anchor on source page path = /autogen/docs/installation/Docker:
  -> linking to /autogen/docs/Contribute#docker
• Broken anchor on source page path = /autogen/docs/reference/agentchat/conversable_agent:
  -> linking to ./groupchat#groupchat-objects (resolved as: /autogen/docs/reference/agentchat/groupchat#groupchat-objects)
• Broken anchor on source page path = /autogen/docs/Use-Cases/agent_chat:
  -> linking to ../reference/agentchat/conversable_agent#conversableagent-objects (resolved as: /autogen/docs/reference/agentchat/conversable_agent#conversableagent-objects)
  -> linking to /autogen/docs/reference/agentchat/assistant_agent#assistantagent-objects
  -> linking to /autogen/docs/reference/agentchat/user_proxy_agent#userproxyagent-objects
  -> linking to #enhanced-inference (resolved as: /autogen/docs/Use-Cases/agent_chat#enhanced-inference)
  -> linking to /autogen/docs/reference/agentchat/conversable_agent#conversableagent-objects