Upgrade to stb_image 2.28

[ChrisThrasher]

Description

https://src.fedoraproject.org/rpms/SFML/pull-request/2

Fixes some CVEs in stb_image 2.27

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (2.6.x@6aaf132). Click here to learn what that means.
The diff coverage is n/a.

❗ Current head feee934 differs from pull request most recent head 037fdf5. Consider uploading reports for the commit 037fdf5 to get more accurate results

Additional details and impacted files

@@           Coverage Diff            @@
##             2.6.x    #2464   +/-   ##
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  Coverage         ?   23.15%           
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  Files            ?      212           
  Lines            ?    18063           
  Branches         ?     4405           
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  Hits             ?     4183           
  Misses           ?    13427           
  Partials         ?      453           

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[eXpl0it3r]

Can you do this for 2.6.x?

[ChrisThrasher]

@binary1248 Extended CI is failing because it's trying to run clang-tidy on 2.6.x.

[ChrisThrasher]

For the record, the addition of this PR introduced a new compiler warning that will get trigged if you're using a version of CMake older than 3.24. In 3.24 CMake fixed an issue that caused MSVC to emit warnings on 3rd party code. Without that fix, MSVC will detect and emit and warning about some lossy conversions in stb_image.h.

https://cmake.org/cmake/help/latest/release/3.24.html#generators

The Visual Studio Generators now support SYSTEM headers when using VS 2019 Update 11 or later.

Is this something worth fixing in SFML itself to avoid downstream users having to deal with it? I hope we can use pragmas as a workaround since I think modifying stb_image.h itself it out of the question.