Build: collapse the nested if in images tone (clippy)

crates/images/src/tone.rs

@@ -13,10 +13,10 @@ pub enum Tone {
 
 /// The [`Tone`] of an image file, `None` when a swatch doesn't colour it.
 pub fn tone(bytes: &[u8]) -> Option<Tone> {
-    if let Some(info) = craft_image_codecs::inspect_raster(bytes).ok().flatten() {
-        if info.channels > 1 {
-            return None;
-        }
+    if let Some(info) = craft_image_codecs::inspect_raster(bytes).ok().flatten()
+        && info.channels > 1
+    {
+        return None;
     }
     match craft_image_codecs::classify_tone(bytes)? {
         craft_image_codecs::ToneClass::Bitmap => Some(Tone::Bitmap),