Readme: fix typo in code

README.md

@@ -32,8 +32,8 @@ image_data     image  = image_load("input.png");
 backend_device device = backend_init();
 depthany_model model  = depthany_load_model("Depth-Anything-V2-Small-F16.gguf", device);
 image_data     depth  = depthany_compute(model, image);
-image_data     image  = image_f32_to_u8(depth, image_format::alpha_u8);
-image_save(image, "depth.png");
+image_data     output = image_f32_to_u8(depth, image_format::alpha_u8);
+image_save(output, "depth.png");
 ```
 
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