Update vendor files to point to kubernetes-1.12.0-beta.1

vendor/k8s.io/api/authentication/v1beta1/zz_generated.deepcopy.go

@@ -117,12 +117,15 @@ func (in *UserInfo) DeepCopyInto(out *UserInfo) {
 		in, out := &in.Extra, &out.Extra
 		*out = make(map[string]ExtraValue, len(*in))
 		for key, val := range *in {
+			var outVal []string
 			if val == nil {
 				(*out)[key] = nil
 			} else {
-				(*out)[key] = make([]string, len(val))
-				copy((*out)[key], val)
+				in, out := &val, &outVal
+				*out = make(ExtraValue, len(*in))
+				copy(*out, *in)
 			}
+			(*out)[key] = outVal
 		}
 	}
 	return