Fix types in tool tests

[davorrunje]

Why are these changes needed?

Fixes types in tests of tools related tests.

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 49.98%. Comparing base (16b1db3) to head (cd760f5).

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2285       +/-   ##
===========================================
+ Coverage   38.16%   49.98%   +11.81%     
===========================================
  Files          78       78               
  Lines        7861     7861               
  Branches     1681     1819      +138     
===========================================
+ Hits         3000     3929      +929     
+ Misses       4611     3600     -1011     
- Partials      250      332       +82     

Flag	Coverage Δ
unittest	14.22% <100.00%> (?)
unittests	48.96% <100.00%> (+10.81%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.