chore: modify default version to 0.4.0
diff --git a/Makefile b/Makefile
index 037923e..bb04c5e 100644
--- a/Makefile
+++ b/Makefile
@@ -16,7 +16,7 @@
 #
 default: help
 
-VERSION ?= 0.3.0
+VERSION ?= 0.4.0
 RELEASE_SRC = apache-apisix-ingress-controller-${VERSION}-src
 IMAGE_TAG ?= dev