bump version to 0.2.0b6

[sonichi]

Why are these changes needed?

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 (7c528a6) 29.81% compared to head (a28bb72) 55.59%.

Additional details and impacted files

@@             Coverage Diff             @@
##             main     #710       +/-   ##
===========================================
+ Coverage   29.81%   55.59%   +25.78%     
===========================================
  Files          27       27               
  Lines        3448     3448               
  Branches      780      822       +42     
===========================================
+ Hits         1028     1917      +889     
+ Misses       2346     1322     -1024     
- Partials       74      209      +135     

Flag	Coverage Δ
unittests	55.39% <100.00%> (+25.63%)	⬆️

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[afourney]

FYI the 3.9 test fails with:

test_groupchat.py
import mock
E ModuleNotFoundError: No module named 'mock'

[qingyun-wu]

FYI the 3.9 test fails with:

test_groupchat.py import mock E ModuleNotFoundError: No module named 'mock'

This should have been addressed in the other PR.

[sonichi]

FYI the 3.9 test fails with:
test_groupchat.py import mock E ModuleNotFoundError: No module named 'mock'

This should have been addressed in the other PR.

Could you include the PR number?