Remove obsolete six dependency (#19604)
Remove obsolete six dependency (#19604)


szha/mxnet,DickJC123/mxnet,szha/mxnet,szha/mxnet,tlby/mxnet,apache/incubator-mxnet,tlby/mxnet,apache/incubator-mxnet,tlby/mxnet,leezu/mxnet,tlby/mxnet,leezu/mxnet,tlby/mxnet,tlby/mxnet,DickJC123/mxnet,leezu/mxnet,szha/mxnet,szha/mxnet,leezu/mxnet,apache/incubator-mxnet,szha/mxnet,tlby/mxnet,DickJC123/mxnet,tlby/mxnet,szha/mxnet,tlby/mxnet,leezu/mxnet,leezu/mxnet,apache/incubator-mxnet,tlby/mxnet,leezu/mxnet,DickJC123/mxnet,szha/mxnet,szha/mxnet,leezu/mxnet,leezu/mxnet