Fixes compilation error on MacOS

[roughbits01]

• Has this change been discussed on the forum or in an issue before?
• Does the code follow the SFML Code Style Guide?
• Have you provided some example/test code for your changes?
• If you have additional steps which need to be performed list them as tasks!

---

Description

This change fixes the following compilation error on MacOS with Clang 13 (mainline clang installed through HomeBrew brew install llvm).

error: implicit conversion from 'size_t' (aka 'unsigned long') to 'CGFloat' (aka 'double') may lose precision [-Werror,-Wimplicit-int-float-conversion]

Tasks

• Tested on Linux
• Tested on Windows
• Tested on macOS
• Tested on iOS
• Tested on Android

How to test this PR?

Compile SFML with -Werror,-Wimplicit-int-float-conversion

[codecov]

Codecov Report

Merging #2040 (1dcf142) into master (2e6c363) will increase coverage by 0.00%.
The diff coverage is 0.00%.

@@           Coverage Diff           @@
##           master   #2040    +/-   ##
=======================================
  Coverage    7.51%   7.51%            
=======================================
  Files         185     185            
  Lines       15848   15847     -1     
  Branches     4170    4170            
=======================================
  Hits         1191    1191            
- Misses      14297   14524   +227     
+ Partials      360     132   -228     

Impacted Files	Coverage Δ
src/SFML/Window/OSX/SFWindowController.mm	0.00% <0.00%> (ø)
src/SFML/System/Err.cpp	0.00% <0.00%> (ø)
src/SFML/Audio/Music.cpp	0.00% <0.00%> (ø)
src/SFML/Audio/Sound.cpp	0.00% <0.00%> (ø)
src/SFML/Network/Ftp.cpp	0.00% <0.00%> (ø)
src/SFML/Network/Http.cpp	0.00% <0.00%> (ø)
src/SFML/Audio/ALCheck.cpp	0.00% <0.00%> (ø)
src/SFML/Graphics/Font.cpp	0.00% <0.00%> (ø)
src/SFML/Graphics/Text.cpp	0.00% <0.00%> (ø)
src/SFML/System/String.cpp	3.36% <0.00%> (ø)
... and 52 more

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 2e6c363...1dcf142. Read the comment docs.

[ChrisThrasher]

Did you also compile the tests and examples with that extra warning you added? If we're going to fix this warning, I'd prefer that we add it to CompilerWarnings.cmake and see what else gets caught when the CI pipeline runs.

[ChrisThrasher]

I switched to this same version of Clang and was able to recreate this error without enabling additional compiler warnings so we must already be using this warning. The tests and examples build fine too. Thanks for the contribution!

[eXpl0it3r]

Thanks for this fix! 🥳