update SDL_mixer to SDL3_mixer 3.2.0

libs/SDL3_mixer/cmake/test/main.c

@@ -0,0 +1,17 @@
+#include <SDL3/SDL.h>
+#include <SDL3/SDL_main.h>
+#include <SDL3_mixer/SDL_mixer.h>
+
+int main(int argc, char *argv[])
+{
+    if (!SDL_Init(0)) {
+        SDL_Log("SDL_Init: could not initialize SDL: %s\n", SDL_GetError());
+        return 1;
+    }
+    if (MIX_Init() == 0) {
+        SDL_Log("MIX_Init: no sound/music loaders supported (%s)\n", SDL_GetError());
+    }
+    MIX_Quit();
+    SDL_Quit();
+    return 0;
+}