Fix macOS Build Issue during linking SDL2

[ZzzhHe]

Description:

This pull request addresses the build issue encountered when compiling the SDL2 project on macOS, specifically for users who have installed SDL2 via Homebrew brew install sdl2

fixes #22

Changes made:

1. Modified CMakeLists.txt to detect if the build is happening on macOS and if SDL2 is installed via Homebrew.
2. Added conditional statements to set the SDL2_INCLUDE_DIR and SDL2_LIB_DIR variables to the appropriate paths used by Homebrew.
3. Adjusted the target_link_libraries command to ensure proper linking against the SDL2 library.

The changes ensure compatibility with the standard SDL2 installation method as well as with Homebrew's path structure, providing a more seamless build experience for macOS users.

Testing:

• The build was tested on macOS with SDL2 installed via Homebrew, confirming that the issue is resolved.
• Ensured that the build process remains unaffected on other operating systems.