原因: elasticsearch-dsl 版本不对
版本要求

  • Elasticsearch 6.x
    • elasticsearch-dsl>=6.0.0,<7.0.0
  • Elasticsearch 5.x
    • elasticsearch-dsl>=5.0.0,<6.0.0
  • Elasticsearch 2.x
    • elasticsearch-dsl>=2.0.0,<3.0.0