Update SDL2 to 2.28.5

Makefile

@@ -12,7 +12,7 @@ CMAKE_URL := https://github.com/Kitware/CMake/releases/download/v$(CMAKE_VERSION
 
 # Project branches (for git-based projects)
 LOVE_BRANCH := main
-SDL2_BRANCH := release-2.28.4
+SDL2_BRANCH := release-2.28.5
 LUAJIT_BRANCH := v2.1
 OPENAL_BRANCH := 1.23.1
 BROTLI_BRANCH := v1.0.9