Added new models to token_count_utils

[afourney]

Why are these changes needed?

Added gpt-4-0125-preview and gpt-4-turbo-preview to token_count_utils.

• 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 ✅

Comparison is base (5eaf712) 33.08% compared to head (b31e51d) 45.62%.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #1511       +/-   ##
===========================================
+ Coverage   33.08%   45.62%   +12.53%     
===========================================
  Files          42       42               
  Lines        5048     5048               
  Branches     1156     1223       +67     
===========================================
+ Hits         1670     2303      +633     
+ Misses       3250     2561      -689     
- Partials      128      184       +56     

Flag	Coverage Δ
unittests	45.54% <ø> (+12.50%)	⬆️

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