VOL-3299: VOLTHA2.4 release for voltha-system-tests repo

Change-Id: I25dec5ca8c27a44fb4ea049e5a06332c5a273950
diff --git a/VERSION b/VERSION
index eef2640..197c4d5 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.4.0-dev0
+2.4.0