GIT_SILENT Update Appstream for new release

(cherry picked from commit 784a15a9)

data/org.kde.kdeconnect.kcm.appdata.xml

@@ -158,9 +158,9 @@
     <value key="KDE::google_play">https://play.google.com/store/apps/details?id=org.kde.kdeconnect_tp</value>
   </custom>
   <releases>
+    <release version="21.04.0" date="2021-04-22"/>
     <release version="20.12.3" date="2021-03-04"/>
     <release version="20.12.2" date="2021-02-04"/>
     <release version="20.12.1" date="2021-01-07"/>
-    <release version="20.12.0" date="2020-12-10"/>
   </releases>
 </component>