Update src/manifest.json

Co-authored-by: piyo <chick.p.1120@gmail.com>

Author: juridon

src/manifest.json

@@ -13,8 +13,7 @@
   "icon": "image/icon.png",
   "homepage_url": {
     "ja":"https://cybozu.dev/ja/kintone/tips/development/plugins/sample-plugin/spreadsheet-plugin/",
-    "en":"https://cybozu.dev/ja/kintone/tips/development/plugins/sample-plugin/spreadsheet-plugin/",
-    "zh":"https://cybozu.dev/ja/kintone/tips/development/plugins/sample-plugin/spreadsheet-plugin/"
+    "en":"https://cybozu.dev/ja/kintone/tips/development/plugins/sample-plugin/spreadsheet-plugin/"
   },
   "desktop": {
     "js": [