Bump python SDK harness

[stankiewicz]

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[gemini-code-assist]

Summary of Changes

Hello @stankiewicz, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request updates the Python SDK harness container tag to a more recent version. This change ensures that the Dataflow runner utilizes the latest development build of the Python SDK harness, maintaining compatibility and incorporating recent improvements or fixes for unreleased SDKs.

Highlights

• Python SDK Harness Version Bump: The BEAM_DEV_SDK_CONTAINER_TAG has been updated from beam-master-20250917 to beam-master-20250929 in sdks/python/apache_beam/runners/dataflow/internal/names.py.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 56.85%. Comparing base (17c8515) to head (5c47096).
⚠️ Report is 45 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff              @@
##             master   #36314      +/-   ##
============================================
+ Coverage     56.82%   56.85%   +0.02%     
  Complexity     3386     3386              
============================================
  Files          1220     1220              
  Lines        185731   185818      +87     
  Branches       3523     3523              
============================================
+ Hits         105538   105638     +100     
+ Misses        76853    76840      -13     
  Partials       3340     3340              

Flag	Coverage Δ
python	80.95% <100.00%> (+0.03%)	⬆️

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