Add date

content/announcements/plasma/5/20.90.md

@@ -5,7 +5,7 @@ desc: Plasma 5.21 is all about upgrading the looks and usability of Plasma.
 description: Plasma 5.21 is a looker! The new wallpaper and new app launcher make Plasma not only easier on the eyes, but also easier to use and much more accessible.
 version: "5.20.90"
 release: "plasma-5.20.90"
-date: 2020-01-21
+date: "2020-01-21T15:00:00Z"
 layout: plasma-5-21
 sassFiles:
   - /sass/plasma-5-21.scss