Update MB version history

Author: Christopher Liu

data/org.sugarlabs.MusicBlocks.appdata.xml

@@ -25,9 +25,15 @@
     <content_rating type="oars-1.1" />
 
     <releases>
-        <release version="3.5.1" date="2020-08-03" />
+        <release version="3.5.1" date="2021-06-21" />
+        <release version="3.5" date="2021-05-29" />
+        <release version="3.4.2" date="2020-12-24" />
+        <release version="3.4.1" date="2020-11-17" />
+        <release version="3.4" date="2020-11-12" />
+        <release version="3.3" date="2020-09-06" />
         <release version="3.2" date="2020-08-03" />
         <release version="3.1" date="2020-05-25" />
+        <release version="3.0" date="2020-02-28" />
     </releases>
     <developer_name>Sugar Labs Community</developer_name>
     <project_license>AGPL-3.0-or-later</project_license>