fix: increase gas limit for bridged erc20 deposits (#45)

The gas limit of 16k seems to be fine for addresses that already have an
entry in the erc20 balance storage map, but is too low for new entries.
Based on preliminary testing, 64k seems to be a good value with some
buffer.

grpc/execution/validation.go

@@ -1,16 +1,17 @@
 package execution
 
 import (
-	astriaPb "buf.build/gen/go/astria/execution-apis/protocolbuffers/go/astria/execution/v1alpha2"
-	sequencerblockv1alpha1 "buf.build/gen/go/astria/sequencerblock-apis/protocolbuffers/go/astria/sequencerblock/v1alpha1"
 	"crypto/sha256"
 	"fmt"
+	"math/big"
+
+	astriaPb "buf.build/gen/go/astria/execution-apis/protocolbuffers/go/astria/execution/v1alpha2"
+	sequencerblockv1alpha1 "buf.build/gen/go/astria/sequencerblock-apis/protocolbuffers/go/astria/sequencerblock/v1alpha1"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/contracts"
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/log"
 	"github.com/ethereum/go-ethereum/params"
-	"math/big"
 )
 
 // `validateAndUnmarshalSequencerTx` validates and unmarshals the given rollup sequencer transaction.
@@ -68,7 +69,7 @@ func validateAndUnmarshalSequencerTx(
 				//
 				// the fees are spent from the "bridge account" which is not actually a real account, but is instead some
 				// address defined by consensus, so the gas cost is not actually deducted from any account.
-				Gas:  16000,
+				Gas:  64000,
 				To:   &bac.Erc20Asset.ContractAddress,
 				Data: calldata,
 			}