Fix useless-cast warning

[waahm7]

Issue #, if available: #973

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[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 83.82%. Comparing base (0a98aa0) to head (3f9f026).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1090   +/-   ##
=======================================
  Coverage   83.82%   83.82%           
=======================================
  Files          57       57           
  Lines        5991     5991           
=======================================
  Hits         5022     5022           
  Misses        969      969           

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[graebm]

Fixed it here: https://github.com/awslabs/aws-c-common/pull/1145