Fix calculation when cost per byte

Author: vsubhuman

rust/src/lib.rs

@@ -270,7 +270,6 @@ impl DataCost {
         match &self.0 {
             DataCostEnum::CoinsPerByte(coins_per_byte) => {
                 coins_per_byte
-                    .checked_add(&BigNum::one())?
                     .checked_mul(&BigNum::from_str("8")?)
             },
             DataCostEnum::CoinsPerWord(coins_per_word) => Ok(coins_per_word.clone()),