fix: drop Python 3.9 shim

[AbeCoull]

Issue #, if available:

Description of changes:

Testing done:

Merge Checklist

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 100.00%. Comparing base (be0beea) to head (6f8c8dd).

Additional details and impacted files

@@            Coverage Diff            @@
##              main     #1326   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files          171       171           
  Lines        11550     11550           
  Branches      1511      1511           
=========================================
  Hits         11550     11550           

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[AbeCoull]

Code check failures are being addressed in #1325