GIT_SILENT Update Appstream for new release

(cherry picked from commit b2092879)

src/org.kde.knetwalk.appdata.xml

@@ -122,10 +122,10 @@
   <project_group>KDE</project_group>
   <content_rating type="oars-1.1"/>
   <releases>
+    <release version="3.3.21080" date="2021-08-12"/>
     <release version="3.3.21043" date="2021-07-08"/>
     <release version="3.3.21042" date="2021-06-10"/>
     <release version="3.3.21041" date="2021-05-13"/>
-    <release version="3.3.21040" date="2021-04-22"/>
   </releases>
   <content_rating type="oars-1.1"/>
 </component>