GIT_SILENT Update Appstream for new release

(cherry picked from commit 1b7ecc35)

org.kde.katomic.appdata.xml

@@ -119,9 +119,9 @@
   </screenshots>
   <project_group>KDE</project_group>
   <releases>
+    <release version="20.12.1" date="2021-01-07"/>
     <release version="20.12.0" date="2020-12-10"/>
     <release version="20.08.3" date="2020-11-05"/>
     <release version="20.08.2" date="2020-10-08"/>
-    <release version="20.08.1" date="2020-09-03"/>
   </releases>
 </component>