Bumping released version in go.mod

Change-Id: I9102939f94b43faca58f3a3320da9c8dac26e607
diff --git a/VERSION b/VERSION
index fcdb2e1..1454f6e 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-4.0.0
+4.0.1