multi: replace ioutil.WriteFile

lnrpc/routerrpc/router_server.go

@@ -6,7 +6,6 @@ import (
 	crand "crypto/rand"
 	"errors"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"path/filepath"
 	"sync/atomic"
@@ -216,7 +215,7 @@ func New(cfg *Config) (*Server, lnrpc.MacaroonPerms, error) {
 		if err != nil {
 			return nil, nil, err
 		}
-		err = ioutil.WriteFile(macFilePath, routerMacBytes, 0644)
+		err = os.WriteFile(macFilePath, routerMacBytes, 0644)
 		if err != nil {
 			_ = os.Remove(macFilePath)
 			return nil, nil, err