withdrawals amount in uint64 gwei: ethereum/execution-apis#354

Author: tersec

eth/common/eth_types.nim

@@ -100,7 +100,7 @@ type
     index*         : uint64
     validatorIndex*: uint64
     address*       : EthAddress
-    amount*        : UInt256
+    amount*        : uint64
 
   BlockHeader* = object
     parentHash*:      Hash256

tests/rlp/test_common.nim

@@ -86,7 +86,7 @@ proc suite1() =
         address: EthAddress [
           0.byte, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10,
           11, 12, 13, 14, 15, 16, 17, 18, 19],
-        amount: 4.u256 * 1_000_000_000.u256)
+        amount: 4)
 
       let abytes = rlp.encode(a)
       let aa = rlp.decode(abytes, Withdrawal)