Bump minor version post VOLTHA2.4 branch out

Change-Id: Ic86f4943d3182e0393bd46d0aef0edea24e8f0a4
diff --git a/VERSION b/VERSION
index e30309f..69fa968 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.4.7
+2.5.0-dev