mod+kvdb: update etcd to v3.5.0

kvdb/etcd/fixture.go

@@ -11,8 +11,8 @@ import (
 
 	"github.com/btcsuite/btcwallet/walletdb"
 	"github.com/stretchr/testify/require"
-	"go.etcd.io/etcd/clientv3"
-	"go.etcd.io/etcd/clientv3/namespace"
+	"go.etcd.io/etcd/client/v3"
+	"go.etcd.io/etcd/client/v3/namespace"
 )
 
 const (