* update PaddleNLP  lexical_analysis for Release/1.6 (#3664)

* update for paddle 1.6

* update optimize op in paddle 1.6

* fix ernie based in paddle 1.6

* fix coding for windows

* update downloads.py (#3672)

* Fix infer bug on Release/1.6  

* fix bug on ernie based inferring

* replace open with io.open to be compatible with windows (#3707)

* update README.md