Bump version to v0.5.0-beta1

Signed-off-by: Julius Härtl <jus@bitgrid.net>

appinfo/info.xml

@@ -14,7 +14,7 @@
 - 🚀 Get your project organized
 
 </description>
-    <version>0.5.0-dev4</version>
+    <version>0.5.0-beta1</version>
     <licence>agpl</licence>
     <author>Julius Härtl</author>
     <namespace>Deck</namespace>