Fixed types related to function calling

[davorrunje]

Why are these changes needed?

Related issue number

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 49.71%. Comparing base (989c182) to head (9e164c9).

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2230       +/-   ##
===========================================
+ Coverage   37.83%   49.71%   +11.88%     
===========================================
  Files          77       77               
  Lines        7766     7766               
  Branches     1663     1800      +137     
===========================================
+ Hits         2938     3861      +923     
+ Misses       4579     3583      -996     
- Partials      249      322       +73     

Flag	Coverage Δ
unittest	14.35% <60.00%> (?)
unittests	48.64% <100.00%> (+10.82%)	⬆️

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