Update error message in AnimatedImageDecoder

Replace an occurrence of 'webp' with generic 'image' since the
class supports more than just webp now.

PiperOrigin-RevId: 511910050

library/src/main/java/com/bumptech/glide/load/resource/drawable/AnimatedImageDecoder.java

@@ -73,7 +73,7 @@ Resource<Drawable> decode(@NonNull Source source, int width, int height, @NonNul
             source, new DefaultOnHeaderDecodedListener(width, height, options));
     if (!(decoded instanceof AnimatedImageDrawable)) {
       throw new IOException(
-          "Received unexpected drawable type for animated webp, failing: " + decoded);
+          "Received unexpected drawable type for animated image, failing: " + decoded);
     }
     return new AnimatedImageDrawableResource((AnimatedImageDrawable) decoded);
   }