Go build is failing with go1.15

I have been working on version 1.10.0 to get istio-operator image built along with operator binary. Can you please help me with go version and step to get it done.

So far I have tried this:-

root@gardener-master istio]# go get -v ./...
manifests/manifest.go:18:2: package embed is not in GOROOT (/usr/lib/golang/src/embed)
operator/pkg/helm/renderer.go:19:2: package io/fs is not in GOROOT (/usr/lib/golang/src/io/fs)

$ GO111MODULE=auto go mod init; go get -v ./...
same issue

Go 1.16 is required to build Istio 1.10+