update-codegen.sh doesn't work after code-generator upgrading to 1.19

[Jeffwan]

➜  mxnet-operator git:(master) go build -o defaulter-gen   /Users/jiaxin/go/pkg/mod/k8s.io/code-generator@v0.16.10-beta.0/cmd/defaulter-gen

-> 1.16.10 work

➜  mxnet-operator git:(master) ✗ go build -o defaulter-gen   /Users/jiaxin/go/pkg/mod/k8s.io/code-generator@v0.19.9/cmd/defaulter-gen
go: directory ../../../../pkg/mod/k8s.io/code-generator@v0.19.9/cmd/defaulter-gen outside available modules

-> 1.19.x doesn't work