change transaction value fields from u128 to a wrapper-type of U256 (#4439)

Co-authored-by: Matthias Seitz <matthias.seitz@outlook.de>

crates/net/network/tests/it/requests.rs

@@ -22,7 +22,7 @@ pub fn rng_transaction(rng: &mut impl rand::RngCore) -> TransactionSigned {
         gas_price: rng.gen(),
         gas_limit: rng.gen(),
         to: TransactionKind::Create,
-        value: rng.gen(),
+        value: rng.gen::<u128>().into(),
         input: Bytes::from(vec![1, 2]),
         access_list: Default::default(),
     });