minio-go has removed CloudStorageClient

shells/cache.go line 39,

func getCacheStorageClient(cache *common.CacheConfig) (scl minio.CloudStorageClient, err error) {

refers to minio.CloudStorageClient which has been removed from github.com/minio/minio-go in this commit on 7th February 2016: https://github.com/minio/minio-go/commit/050ab63026f0cfa18ea7a5b54188fb1a0de27e08

This means that a manual reversion is needed on the minio-go dependency before gitlab-ci-multi-runner will build.