feat: Make last-updated plugin extendPageData function asynchronous

Author: kefranabg

packages/@vuepress/plugin-last-updated/index.js

@@ -2,9 +2,9 @@ const path = require('path')
 const spawn = require('cross-spawn')
 
 module.exports = (options = {}, context) => ({
-  extendPageData ($page) {
+  async extendPageData ($page) {
     const { transformer } = options
-    const timestamp = getGitLastUpdatedTimeStamp($page._filePath)
+    const timestamp = await getGitLastUpdatedTimeStamp($page._filePath)
     const $lang = $page._computed.$lang
     if (timestamp) {
       const lastUpdated = typeof transformer === 'function'
@@ -19,14 +19,16 @@ function defaultTransformer (timestamp, lang) {
   return new Date(timestamp).toLocaleString(lang)
 }
 
-function getGitLastUpdatedTimeStamp (filePath) {
+async function getGitLastUpdatedTimeStamp (filePath) {
   let lastUpdated
   try {
-    lastUpdated = parseInt(spawn.sync(
+    const commandResult = await spawn(
       'git',
       ['log', '-1', '--format=%at', path.basename(filePath)],
       { cwd: path.dirname(filePath) }
-    ).stdout.toString('utf-8')) * 1000
+    )
+    const formattedResult = commandResult.stdout.toString('utf-8')
+    lastUpdated = parseInt(formattedResult) * 1000
   } catch (e) { /* do not handle for now */ }
   return lastUpdated
 }