fix(tests): expect the proper libpng version in core24 linter test

[sergiusens]

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This fixes google:ubuntu-22.04-64:tests/spread/core24/linters/library-unused

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Comparison is base (6ff3e0b) 88.83% compared to head (6ee45c6) 88.90%.
Report is 10 commits behind head on feature/craft-application.

Additional details and impacted files

@@                      Coverage Diff                      @@
##           feature/craft-application    #4597      +/-   ##
=============================================================
+ Coverage                      88.83%   88.90%   +0.06%     
=============================================================
  Files                            327      331       +4     
  Lines                          22033    22115      +82     
=============================================================
+ Hits                           19573    19661      +88     
+ Misses                          2460     2454       -6     

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