Update version with first beta of v2.13.0 (v2.12.0 was created based on previous commit)

Author: kirchsth

C4.puml

@@ -23,7 +23,7 @@
 ' ##################################
 !function C4Version()
   ' 2 spaces and ' are used as unique marker, that the release scripts makes the correct version update
-  !$c4Version  =  "2.12.0beta1"
+  !$c4Version  =  "2.13.0beta1"
   !return $c4Version
 !end function