Fix deprecated 'to_rgb()' to 'to_rgb8()'

Author: nbigaouette

onnxruntime/tests/integration_tests.rs

@@ -64,7 +64,7 @@ mod download {
             input0_shape[3] as u32,
             FilterType::Nearest,
         )
-        .to_rgb();
+        .to_rgb8();
 
         // Python:
         // # image[y, x, RGB]
@@ -270,7 +270,7 @@ mod download {
                 .join(IMAGE_TO_LOAD),
         )
         .unwrap()
-        .to_rgb();
+        .to_rgb8();
 
         let array = ndarray::Array::from_shape_fn((1, 224, 224, 3), |(_, j, i, c)| {
             let pixel = image_buffer.get_pixel(i as u32, j as u32);