Use -mod=vendor for running unit tests
Use -mod=vendor for running unit tests

The unit tests should not download dependencies ad-hoc but use the local
vendored sources for sake of reproducibility.

Signed-off-by: Sascha Grunert <70ab469ddb2ac3e35f32ed7c2fd1cca514b2e879@suse.com>

containers/storage,containers/storage,rhatdan/storage,rhatdan/storage,rhatdan/storage,containers/storage