fix(xo-server/listBackupNgPartitionFiles): missing await

Strange things though, it works in dev compilation mode…

Fixes #2929

packages/xo-server/src/xo-mixins/file-restore-ng.js

@@ -196,7 +196,7 @@ export default class BackupNgFileRestore {
 
     const entriesMap = {}
     await Promise.all(
-      readdir(path).map(async name => {
+      (await readdir(path)).map(async name => {
         try {
           const stats = await stat(`${path}/${name}`)
           entriesMap[stats.isDirectory() ? `${name}/` : name] = {}