add artifact.Identifiable by Identity() method

Signed-off-by: Alex Goodman <alex.goodman@anchore.com>

internal/formats/syftjson/to_format_model.go

@@ -93,8 +93,8 @@ func toRelationshipModel(relationships []artifact.Relationship) []model.Relation
 	result := make([]model.Relationship, len(relationships))
 	for i, r := range relationships {
 		result[i] = model.Relationship{
-			Parent:   string(r.From),
-			Child:    string(r.To),
+			Parent:   string(r.From.Identity()),
+			Child:    string(r.To.Identity()),
 			Type:     string(r.Type),
 			Metadata: r.Data,
 		}