[Common] Fix forfeit tx size estimation (#464)

Author: louisinger

common/fees.go

@@ -34,7 +34,7 @@ func ComputeForfeitTxFee(
 ) (uint64, error) {
 	txWeightEstimator := &input.TxWeightEstimator{}
 
-	txWeightEstimator.AddP2PKHInput() // connector input
+	txWeightEstimator.AddTaprootKeySpendInput(txscript.SigHashDefault) // connector input
 	txWeightEstimator.AddTapscriptInput(
 		lntypes.WeightUnit(witnessSize),
 		tapscript,