update 4.8.0 release date in changelog

pissang · pissang · commit 30663fc158bc · 2020-05-25T14:36:10.000+08:00
diff --git a/en/changelog.md b/en/changelog.md
@@ -1,5 +1,5 @@
 ## v4.8.0
-<div class="time">2020-05-04</div>
+<div class="time">2020-05-25</div>
 
 + [Feature] [toolbox] Support download SVG file in toolbox when using SVG render mode. [#12144](https://github.com/apache/incubator-echarts/pull/12144) ([Zhang Wenli](https://github.com/Ovilia))
 
diff --git a/zh/changelog.md b/zh/changelog.md
@@ -1,5 +1,5 @@
 ## v4.8.0
-<div class="time">2020-05-04</div>
+<div class="time">2020-05-25</div>
 
 + [Feature] [toolbox] 支持 SVG 渲染模式下 toolbox 下载成 SVG 文件。 [#12144](https://github.com/apache/incubator-echarts/pull/12144) ([Zhang Wenli](https://github.com/Ovilia))
 
