Remove unnecessary code comment

These comments say what the code is doing, they add no value.

src/ecdsa/serialized_signature.rs

@@ -272,9 +272,7 @@ mod tests {
     #[test]
     fn iterator_ops_are_homomorphic() {
         let mut fake_signature_data = [0; MAX_LEN];
-        // fill it with numbers 0 - 71
         for (i, byte) in fake_signature_data.iter_mut().enumerate() {
-            // up to MAX_LEN
             *byte = i as u8;
         }