Building Dockerimage on rpi-aarch64 fails

[phixion]

package github.com/cpuguy83/go-md2man/v2/md2man: cannot find package "github.com/cpuguy83/go-md2man/v2/md2man" in any of:
        /usr/local/go/src/github.com/cpuguy83/go-md2man/v2/md2man (from $GOROOT)
        /root/go/src/github.com/cpuguy83/go-md2man/v2/md2man (from $GOPATH)