glide.yaml: Drop cobra

The last references were removed with cmd/.

Signed-off-by: W. Trevor King <[email protected]>

Author: wking

glide.yaml

@@ -2,7 +2,6 @@ package: github.com/opencontainers/image-spec
 import:
 - package: github.com/pkg/errors
   version: ">=0.7.0"
-- package: github.com/spf13/cobra
 - package: github.com/xeipuuv/gojsonschema
   version: d5336c75940ef31c9ceeb0ae64cf92944bccb4ee
 - package: github.com/russross/blackfriday