Fix deprecation warning for structlog

[Miauwkeru]

Fix deprecation warning structlog

Structlog deprecated pad_event, where the new one is pad_event_to

Proposed Changes

Pin structlog to use the newer version where pad_event_to is added
Replace pad_event with pad_event_to.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 81.06%. Comparing base (2dfc393) to head (8fa65b6).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1631   +/-   ##
=======================================
  Coverage   81.06%   81.06%           
=======================================
  Files         402      402           
  Lines       35244    35244           
=======================================
  Hits        28571    28571           
  Misses       6673     6673           

Flag	Coverage Δ
unittests	81.06% <ø> (ø)

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[codspeed-hq]

Merging this PR will not alter performance

✅ 12 untouched benchmarks

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_{Comparing fix-structlog-deprecation-warning (8fa65b6) with main (2dfc393)}