fix: Txs Validate (cometbft#1687)

* fix: The calculation method of tx size returned by calling proxyapp should be consistent with that of mempool

* Revert CHANGELOG.md

entries should go into .changelog

---------

Co-authored-by: lasaro <lasaro@informal.systems>
Co-authored-by: lasaro <lasaro@gmail.com>

types/tx.go

@@ -108,7 +108,7 @@ func ToTxs(txl [][]byte) Txs {
 func (txs Txs) Validate(maxSizeBytes int64) error {
 	var size int64
 	for _, tx := range txs {
-		size += int64(len(tx))
+		size += ComputeProtoSizeForTxs([]Tx{tx})
 		if size > maxSizeBytes {
 			return fmt.Errorf("transaction data size exceeds maximum %d", maxSizeBytes)
 		}