Fix type and default value of the code_execution_config parameter in UserProxyAgent

[davorrunje]

Why are these changes needed?

UserProxyAgent declares code_execution_config to be an optional parameter and sets its default value for to None

autogen/autogen/agentchat/user_proxy_agent.py

Line 33 in 8f6590e

code_execution_config: Optional[Union[Dict, Literal[False]]] = None,

, while ConversableAgent deprecated use of None

autogen/autogen/agentchat/conversable_agent.py

Line 83 in 8f6590e

code_execution_config: Union[Dict, Literal[False]] = False,

Instantiating a user proxy results in a deprecating warning. E.g. by running the following test:

pytest test/agentchat/test_agent_setup_with_use_docker_settings.py -k test_agent_setup_with_env_variable_false_and_docker_running

we get the following warning

============================================== warnings summary ===============================================
test/agentchat/test_agent_setup_with_use_docker_settings.py::test_agent_setup_with_env_variable_false_and_docker_running
  /workspaces/autogen/autogen/agentchat/user_proxy_agent.py:83: UserWarning: Using None to signal a default code_execution_config is deprecated. Use {} to use default or False to disable code execution.
    super().__init__(

-- Docs: https://docs.pytest.org/en/stable/how-to/capture-warnings.html

This PR changes the type and the default value as follows:

autogen/autogen/agentchat/user_proxy_agent.py

Line 33 in a4377d8

code_execution_config: Union[Dict, Literal[False]] = {},

This resolves warnings and it behaves identically as before the change.

Related issue number

Closes #1995

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 47.96%. Comparing base (24418bd) to head (60253d3).

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1996       +/-   ##
===========================================
+ Coverage   37.57%   47.96%   +10.39%     
===========================================
  Files          65       65               
  Lines        6912     6913        +1     
  Branches     1521     1648      +127     
===========================================
+ Hits         2597     3316      +719     
+ Misses       4090     3319      -771     
- Partials      225      278       +53     

Flag	Coverage Δ
unittests	47.83% <100.00%> (+10.26%)	⬆️

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[sonichi]

The test failures need to be fixed before merging.

[davorrunje]

The test failures need to be fixed before merging.

I'll do it today