Updates Beam Python Fn API container used by Dataflow at HEAD

[chamikaramj]

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[gemini-code-assist]

Summary of Changes

Hello @chamikaramj, 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 default Beam Fn API container tag used by the Dataflow runner. This change is crucial for ensuring that Dataflow jobs leveraging the Python SDK are always running against the most current development version of the Beam SDK harness, thereby incorporating recent improvements and maintaining compatibility with the latest Beam features.

Highlights

• SDK Container Tag Update: The BEAM_DEV_SDK_CONTAINER_TAG in sdks/python/apache_beam/runners/dataflow/internal/names.py has been updated from beam-master-20251205 to beam-master-20251210. This ensures that Dataflow jobs using the Beam Fn API will utilize the latest development SDK container.

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 36.31%. Comparing base (15b50e2) to head (9cd99de).
⚠️ Report is 1 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff            @@
##             master   #37088   +/-   ##
=========================================
  Coverage     36.31%   36.31%           
  Complexity     1676     1676           
=========================================
  Files          1067     1067           
  Lines        167123   167123           
  Branches       1208     1208           
=========================================
  Hits          60696    60696           
  Misses       104247   104247           
  Partials       2180     2180           

Flag	Coverage Δ
python	40.61% <100.00%> (ø)

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