Update AppStream file

Author: KitsuneRal

linux/com.github.quaternion.appdata.xml

@@ -36,6 +36,7 @@
   </provides>
 
   <releases>
+    <release version="0.0.9.4-beta1" date="2019-03-03" type="development" />
     <release version="0.0.9.3" date="2018-10-21" />
     <release version="0.0.9.2" date="2018-06-17" />
     <release version="0.0.9.1" date="2018-05-07" />