Fix VulkanoWindowRenderer::swapchain_image_views return type

I have only noticed this as I was writing the changelog.

@coolcatcoder for future reference, `&Vec<T>` is an anti-pattern. There's nothing more you can do with it than with `&[T]` (because the reference is immutable) and it means that we can't use a different underlying buffer without a breaking change.

vulkano-util/src/renderer.rs

@@ -207,7 +207,7 @@ impl VulkanoWindowRenderer {
     #[inline]
     #[must_use]
     // swapchain_image_views or swapchain_images_views, neither sounds good.
-    pub fn swapchain_image_views(&self) -> &Vec<Arc<ImageView>> {
+    pub fn swapchain_image_views(&self) -> &[Arc<ImageView>] {
         // Why do we use "final views" as the field name,
         // yet always externally refer to them as "swapchain image views"?
         &self.final_views