add hexcolor output of the first function

src/main.rs

@@ -86,6 +86,8 @@ fn main() {
     colors.push(color);
 
     img.save("grid_image.png").expect("Failed to save image");
+    let hex_string = colors.first().unwrap().iter().map(|b| format!("{:02X}", b)).collect::<String>();
+    println!("#{hex_string}");
 }
 
 fn get_pitch_quotient() -> u32 {