Makefile: set GO111MODULE=off
Makefile: set GO111MODULE=off

Turn of go modules to avoid breaking build environments to accidentally
try pulling the dependencies instead of using the ./vendor directory.

Signed-off-by: Valentin Rothberg <c8d7c67387706f1534261b1aba83f5c355c00ff5@redhat.com>

mtrmac/skopeo,mtrmac/skopeo,mtrmac/skopeo