Update Codecov action to use 'files' instead of 'file'

[douglatornell]

Replaced the deprecated 'file' key with 'files' in the Codecov action configuration. This ensures compatibility with the latest Codecov action requirements and prevents potential upload issues.

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 77.72%. Comparing base (2f9a20d) to head (ac8582d).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #322   +/-   ##
=======================================
  Coverage   77.72%   77.72%           
=======================================
  Files         132      132           
  Lines       18777    18777           
  Branches      762      762           
=======================================
  Hits        14595    14595           
  Misses       4116     4116           
  Partials       66       66           

Flag	Coverage Δ
unittests	77.72% <ø> (ø)

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[douglatornell]

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