bump version to 0.2.5

[sonichi]

Why are these changes needed?

For new release

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 ✅

Comparison is base (78a2d84) 31.80% compared to head (a32cf34) 39.52%.
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1180      +/-   ##
==========================================
+ Coverage   31.80%   39.52%   +7.71%     
==========================================
  Files          29       32       +3     
  Lines        4112     4301     +189     
  Branches      961     1044      +83     
==========================================
+ Hits         1308     1700     +392     
+ Misses       2710     2475     -235     
- Partials       94      126      +32     

Flag	Coverage Δ
unittests	39.45% <100.00%> (+7.69%)	⬆️

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