VOL-3303: Bump voltha-openolt-adapter version for 2.4 release

Change-Id: I8adb33519e2613ca60cd5a6e871e1922b34d5117
diff --git a/VERSION b/VERSION
index 1a45714..3f5987a 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-2.4.9-dev
+2.4.9