fix sdl3 gpu prepare draw data function (#82)

Author: AdanW7

src/backend_sdl3_gpu.zig

@@ -44,7 +44,7 @@ pub fn render() void {
 pub fn prepareDrawData(
     command_buffer: *const anyopaque, // SDL_GPUCommandBuffer
 ) void {
-    Imgui_ImplSDLGPU3_PrepareDrawData(gui.getDrawData(), command_buffer);
+    ImGui_ImplSDLGPU3_PrepareDrawData(gui.getDrawData(), command_buffer);
 }
 
 pub fn renderDrawData(
@@ -65,7 +65,7 @@ pub fn renderDrawData(
 extern fn ImGui_ImplSDLGPU3_Init(info: *const anyopaque) bool;
 extern fn ImGui_ImplSDLGPU3_Shutdown() void;
 extern fn ImGui_ImplSDLGPU3_NewFrame() void;
-extern fn Imgui_ImplSDLGPU3_PrepareDrawData(
+extern fn ImGui_ImplSDLGPU3_PrepareDrawData(
     draw_data: *const anyopaque,
     command_buffer: *const anyopaque, // SDL_GPUCommandBuffer
 ) void;